How To Increase The Effect Of Abilify On Child With ADHD?

Hi my son is11 years old and has ADHD AND ODD and is in therapy and his psychiatrist prescirbe him abiify. He is currently taking 5mg BID one in the am and one at HS. If have noticed him to have some trembling in his hands since he has been on this med. I really don t think the med is helping with his moods and it is making him more defiant. Should we take him off this med or start tapering down the dose.Andy