Some people with mental health problems do over take medications or use street drugs. It sounds to me like that are just concerned .. I would take it as they care, they are worried about me and be glad, lots of people don't have anyone that will take the time to notice how they are doing and speak up, ask questions.

The easiest way to deal with this situation is explain that you are taking meds correctly and offer to take a drug test to prove your not using street drugs.

I know all there concern and questions upset you, But they are asking because they care.

Be grateful