My nephew had ADHD and other issues like that as a child. My sisters doctor told her to put him on a good carb, high fat (olive oil, fish oil, etc) diet and it turned it around within months he was much better and never had to go on any of the medications that were suggested. I know it may be difficult but whole foods are the answer, he could really be allergic to something that he was eating with the pediatriacian said was most likely the case. When she just started feeding him whole foods and the oils...that was the answer!
Best Wishes!
It' s pretty cleasr that he displays Disruptive Behavior Disorder of some sort (either O.D.D. or DBD NOS). What is required is a sytematic behavior management plan to implement in the home. A developmentally appropriate version of Lynn Clark's SOS Help for Parents would do the trick.