Failing out, don't know what to do next

I was a good student in college and the first half of medical school. Now it looks like I won't graduate from med school at all. After 2+ years of therapy and trying 6 different kinds of medication for depression, anxiety, and ADHD, I still can't think clearly or concentrate well enough to pass the final exam needed to graduate. I have no idea what I will do after this. I feel like I will never amount to anything or contribute to society in a useful way.