Roadteez, you are still a long way away. After high school, there's 4 years of college, then 4 years of med school, then 3 years of internal medicine residency, then finally 3 years of GI fellowship. Take it one step at a time. Do your best and try to get into a good college. If you're interested in medicine maybe you could volunteer at a free clinic or a hospital or shadow a doctor for a little bit.
As far as whether you should take a social science class, whether you do or not will have zero bearing on whether you match into a GI fellowship or not. Your high school grades are only important for getting you into a good college. That's where the real game starts.
Most of all, you should enjoy being young. Don't rush into adulthood. You'll be there soon enough!
