Signs for ADHD in children are: Aggression, hyperactivity, hypersensitivity, slow learning skills, unable to remain calm when needed, usually center of attention, no fear, etc. You can visit www.ch********
or adhd.com for further information about it. That might help you ask further questions if you are questionable with the doctors diagnosis.
One of my sons has ADHD. He takes Risperderal and Ritalin LA and Ritalin. He is 6 years old and was diagnosed when he was 3 1/2 but not placed on meds until he was 4. He has a great child psychologist and psychiatrist, but it took us through trial and error to find them.
Take care and hang in there.