Does my 4 year old have ADHD?

That really isn't ADHD- that's being upset over a hugely different situation, and a mive sensitivity to artificial food additives. The anger, the constant movement, the biodad that's that way himself. In some people, those chemical additives perform like speed does. It makes your brain go nuts! You could possibly compare it to drinking two energy drinks, on top of not having much control over your involuntary actions. You need to remove all the artificial things from his diet, help him recognize that crazy feeling and conquering it, and deal with his discomfort at being away from home. It's very hard work, but it is so worth it. My mother did all that for me, and now I do it for myself. It becomes much easier to control those hyperactive urges the older you get, so have hope. Ritalin and the like is only for treating the symptoms- it doesn't fix the problem. I wish you the best of luck. It really is worth it- your son will be much happier and so will you.