You should definitely stop taking unprescribed medication. Are you able to see a doctor about your anxiety? If so, then do that instead. As for stuttering, it's major suck when you're in high school. You have to really confront the source of your fear here. Usually, it's just social. And I know hearing this doesn't help at all, but try not to care so much what others think about you. It's hard at that age, but don't forget that high school is just a tiny blip on the radar of your life.