Many drs disavow this, but there are so many parents out there who will swear that when their children eat certain foods -- especially dairy, wheat, gluten-- their behavior is awful. I would stick to the diet change if you notice the difference-- it certainly can't hurt.
In my child's case, it does not matter what he eats-- if it did, I would avoid it:)
have u had him tested for diabetes. I have a friend and when she gives her child anything with sugar she will go like what your little lad is. Get him tested for it so if it comes bk ok you will have to think about giving him a wheat and sugar free diet or try and get tests done to rule things out
hope this is a bit of use to u and good luck.