Mumofthree - I hardly think it is necessary to consult a dietician before giving my child a healthier diet with less sugar and more protein. This is simply closer to what is recommended anyway. However, before I do anything drastic, I can assure you that I will talk to a professional.
Cdfox - this has been suggested before, and is one if the options I am considering if the change in diet does not work. The plan is to see if it is something easily fixed, like too much sugar. If that works, there is no need to even get him tested. If not, we will see if the diagnosis is even there - then look at all the options and start with the least invasive. I didn't realize there were so many ways to diagnose, and so many different treatment options! Thanks to everyone!