Every time they tell you to "stop doing drugs" immediately tell them to buy a drug test so you can prove you're not on drugs, tell them to buy a drug test every day until they do. When they submitted you to the hospital, you should have asked the hospital to do a drug panel test because your parents were accusing you of drugs and you weren't. The hospital would have ran the tests and shown your parents you were clean.
Do they mean the medication you're on is "heavy drugs"?
If they are being abusive, the best thing to do is keep your distance and just focus on your life and taking care of yourself, moving on with your life.

Success is the best revenge - Frank Sinatra