I'm a little fuzzy about where you want to apply for PA school. Are you gunning to apply at a program associated with your own school?
I think the PA guys might be right about you being red flagged at PA schools. They would have a better grasp of how that works more than anyone else. The only exception to the red flag might be at a PA school directly associated with yours. Other than that, you really can't assume that the letters from your program director or the PA program director will hold as much sway as you hope, because they really should be confidential for them to have impact. You have no way of knowing what they would say in a confidential letter, especially if they pity you because of the situation you are in. A student would ideally want stellar letters, and you should keep in mind that you made it 3/4 of the way through a program and bailed. Any letter from them would be tinged by that fact. They really couldn't give you unreserved support, and you should take a second to imagine what they could possibly say about you that would negate the fact that you are trying to find out what career suits you. For example, they wouldn't be able to speak much towards your academic abilities, because you would have performed better if you had an easy time with school. They can't speak to your passion, because you are letting yourself be blown around by shifting winds in your head as to what you want to do every day at work. Keep in mind, whether you are an NP, PA, or podiatrist in clinic, your day will pretty much involve a lot of the same things. Anyone writing you a letter would have to wonder how much different you would fare as a PA, OT, or NP versus being a POD... the daily grind in each is very similar (with the exception of a POD running the show in surgery, which you said you hate the idea of doing). Day to day you will go in, talk to a patient, work things up, prescribe, and move on to the next. You just walked away from the career that would give you the most income, and are going to substitute it for something that will take more time, money, and effort to pursue so you can go be someone elses employee. I'd go back and try to get back in to POD school.
At the core, you need to change your mindset into one of ownership over your life and career rather than looking for the career or situation you are in to dictate how satisfied you will be. You will never be satisfied unless you do this, because the world around you isn't going to cater to you to make you happy. Your patients certainly will not care about how happy you are. So its concerning that you give the impression that you are looking for the job that will make you happy. Make your own magic here. If you were talking about leaving podiatry to go after something like business, or something a lot different, then sure.... there's going to be a big difference in how the careers play out. But all the options you are mentioning are clinical positions where you work with patients in some form.
But don't despair. Its clear you have some angst surrounding all the issues you are sorting through. Your situation in pod school sounds like you were boxed in, and going back to that and making something out of it might not be an option if internships and residencies are out of reach. Since you asked me in the PM for my advice, I'll lay out my suggestions, and it will be up to you to look into how any of them fit with what you have on your plate.
This is a long post, and will get longer, but I type fast, and its only you who has to read through it.
If I were you....
I'd try to get back into pod school. That may not be an option, and its ok if its not, because then you can skip to the next suggestion. They might not let you go back, or you might not get any good residency if you did because of your grades, or the failure of the boards might have closed that door. I don't know any of those details, but that would be my first choice, mostly because its ground you at least would be familiar with. Only you know, and that's a call that you are best positioned to make. Podiatry isn't as awesome as some folks hope it to be, but it can be if you hustle. Most of the pods I know do well... at least better than most of the PA's and NP's that I know. But the debt can be quite high. For saying you are only 100K in debt, thats really not too bad considering almost all the PAs i know have at least that much, and even some RN's I know have that much. Anyway, its a thought.
Second option I would pursue is NP.... preferably a direct entry program. They aren't cheap, but they are at the very least as cheap as almost any PA program you could hope to get into. Yes, there are cheap state school PA programs, but everyone wants cheap PA school, so those tend to be the most competitive. You aren't in a position where you will want to rely on luck from here on out, so my advice centers on plans that will offer the most certainty. Direct entry NP school will be even easier for you to go through because you have some significant premed and pod school knowledge. Life in DE NP school won't be as hard for you because of what is in your head already, and you can get out and enjoy yourself more. When you complete the RN portion of the DE program, you will be able to work more as an RN and pay down debt. At the end, you are an NP. Find a state where you have independent practice rights (half of states are like this), and start working. Total debt after 3 years is $100,000 added to the $100,000 you already have. You will be able to work after you get your RN, and can use that to offset your debt. Lets assume you can put $15,000 per year for a year and a half working as an RN (say you take it easy and don't work like crazy as an RN so you can focus on school). If you can put $22,000 per year towards your debt you will be looking at roughly $178,000 debt after 3 years, and then you will be starting at around $85,000, and making $120,000 within a few years if you hustle as an NP. I'm assuming that living expenses will mostly be covered with your RN wages once you are done with your RN portion of the RN to NP program. If not, add in living expenses on top of that.
Third option, go to an accelerated BSN program and get your RN in a year. Then go to work and immediately start an NP program while you work. I live in a place where nurses make about average for the nation. If you start at $40,000 a year as an RN, you are making $19 an hour.... I honestly would have to look really hard nationwide to find a place that paid that low for even a new grad. The lowest I've heard of a new nurse making in the last 2 years is $27 dollars an hour as base wage. Any nurse working nights or weekends makes quite a bit more in differential. Where I work is pretty much middle of the road as far as wages... maybe even a bit less, and if I worked nights and overtime one day per week, I'd easily make more than a new grad PA or FNP (and might be working less hours than them), and I've been a nurse less than 5 years. If you do the accelerated BSN and then the NP, you would be out and practicing as an NP in probably just over 3 years. The cost of doing this could be fairly steep if you go to an expensive accelerated BSN program, but NP school after that is very affordable. I've seen them as low as $20,000, but I wouldn't limit myself to ones that cheap. $30,000 is what I would expect. So if you do a $45,000 accelerated BSN, then a $30,000 NP program, and work making $75,000 for two years as an RN through your NP program, you are that much farther ahead financially. You've added $75,000 on top of your $100,000 debt, but made $125,000 in the meantime as an RN (but obviously you have to subtract from that $125,000 for living expenses for 2 years). But then at the end of 2 years working as a nurse, you are looking at NP wages, and in a few years could be making $120,000 as an NP if you are hustling. I think at the core you would be looking at $175,000 in pure debt, and subtract from that what you would have been able to put towards the debt during your two years as a nurse. Assume you could put down about $20,000 per year towards your debt, and you are looking at $115,000 of debt from this route after 3 years.
3rd option is PA. You probably have all the prereqs. I'd give it a try no matter what because its a good option. I would expect to pay at least $100,000 for tuition and fees, and then include in whatever you think your living expenses would be. For me, I would expect to pay at least $50,000-$60,000 on top of that for living expenses for 2 years (which I still would feel like would be low). That puts you $150,000 in debt and added to the $100,000 you already have, thats $250,000 in debt. But you start making $85,000 the first year as a new PA, and then within a few years can be making $120,000 if you hustle.
OT can actually be pretty expensive depending on where you go. It would probably be hard to work during the program as well. I would imagine that you would be going into debt at least $60,000 for tuition and fees, but I really don't know. I don't know how lucrative it is either. I have two friends that are OT's, and they seem to do ok. I would guess that they make between $80k and $100k. I get the impression that if you hustle, you can do even better. I just don't know much overall about the tuition one can expect, or the wages. They do seem to have plenty of jobs out there for them. My friends seem to like their jobs as well. I can't really speak much to the OT thing, but there are boards on here that have plenty of folks that can. But I think that OT school will be a lot different of an approach than what you are used to. They take some decent sciences, but they also deal with a lot of theoretical approaches that might be more akin to what you would see in psychology. Not the same, but just those kinds of classes.... more like PT I guess. I would guess they would be a closer match to PT school than PA or NP school.
I suggest applying to PA school, and to direct entry NP programs, and accelerated BSN programs. I would not waste an time trying to get health care experience for PA school... that's just that much less time and risk of wasted time for you. I'd hate to see you go become a CNA or paramedic, and still struggle to get into PA school. At this point, shoot for sure things. Apply to any PA program that doesn't care much about HCE.... there are PLENTY of them that do not care. There are PLENTY more that just require a very token amount of minimal entry level HCE. Taken together, those "no or low HCE" programs comprise the majority of PA programs. PA is already going to be the most expensive choice you have, as well as the one that will be the least certain. I wouldn't chase it too hard. Applying is arduous, though, and you won't want the same letters of recommendation for nursing schools that you would use for the PA program. Its going to be a pain, to be honest. CASPA is the centralized application service PA programs use, and its a full body cavity search. Honestly, the most bang for your buck will come from either direct entry NP, or an accelerated BSN and then an NP program.
Usually, the money thing points to nursing. Plus, nursing gives you a ton of options if you don't like what you are doing.