My 7 Year Old Son Has ADHD.. He Went Through

My 7 year old son has ADHD.. he went through learning disability testing and a psych evaluation before beginning medication. He has been on Concerta for a year now, 27 mg. This past month things have gotten very hard, he's impatient, he doesn't listen to anyone when he is coming off the medication. He doesn't have respect for anyones privacy, typical ADHD behavior, just seems worse lately. Today he came home from school, and he got a "bad color" and it resulted in a nosebleed, he gets them when he is stressed. Its been awhile since he's had one. He told me he hears voices in his head. He says its mainly my voice and Im calling his name, or telling him to pay attention. But he says he hears them all the time for a long time now. Is he deflecting his behavior? or should I be looking into this? Triage nurse says to stop his meds until he can be seen, this is a side effect of Concerta. Should I be really worried???