I agree that neither a tic nor a stimulant would be a deliberate attempt to annoy you. In the case of either tics or stims, a child can suppress them temporarily, such as when a parent or teacher tells the child to stop.
My son has Tourette Syndrome. Our one trial with a stimulant (before his BiPolar (BP) diagnosis) lasted two doses. His tics became so bad that we stopped immediately. So, yes, your son is taking medications that could worsen tics.
I'm not sure whether you are describing tics or stims. Could be both.
