Who should we consult? Should we meet?

My 6 year old is a highly intelligent and an energetic child with no known disorders. Lately his strongwilled nature has been a bit difficult to handle. When reprimanded he has begun reacting physically and aggressively and tends to remain 'angry' for long stretches calling himself a 'bad boy' even when we assure him he is good but that his behaviour is not acceptable. He has to remain mobile at all times else he easily gets bored and starts throwing tantrums. Academically he has no issues and can grasp concepts very quickly and also finish h is work well before time as reported by his teachers. However his behaviour has started perplexing all and is affecting his ability to socialize and causes disturbance for a regular class routine especially at school. His school has advised us to seek medical counselling. Please advise who should we meet? A child psych or an OT . We reside in Powai area