I would recommend that you take the child to a teaching hospital with a good pediatric dept. My friend is a nurse at such a hospital. It was only through constantly talking to the nurses and doctors there that she finally got an accurate diagnosis and effective treatment. Be patient and persistent.
I was with the child a few weeks ago and really could not tell he had a problem.
He alraedy does the blanket over his head at times while he is rocking. He also used to lay on the ground to play outside. They said that it may be an equalibrium problem.
Have you discussed sensory disorders with his dr. I have a firend whose son behaves very similarly to what you describe. Too much stimulation and he acts out. He cannot be in a classroom setting. Occupational therapy has helped him a lot. He is now about 8 and will tell his parents when he needs to leave a situation. His OT started by giving him a blanket to pull over his head to block out some of the stimulants and help him control his environment some.
I hope you get some answers. It was a long road for my friend, but you will find the right diagnosis and treatment for him. Keep me posted.