in response to atwittsend... As a bi-polar grandparent of five, all ages 6 and under and three with ADHD/ADD, I can certainly agree that your last option can work! (God). I am 52 and was diagnosed in my late 30's as being bi-polar with manic depression. It took about 4 years to find a medication that worked and as long as I take it as prescribed, I am level headed and hold down a complicated, stressful job as well as deal with the kids.
These three grandchildren live with me and my wife so when I say grandparent, in reality we are the 'parents'. The boys can act up daily, multiple times and then we see them acting perfectly normal, leaving us to wonder if part of the issue is just kids pushing their boundaries to see how far they can go. These spells most times involve kicking and screaming, not eating and tearing up whatever they get their hands on.
When all three take their prescribed meds, they are fine 90% of the time. As a former school board president I said years ago I woud never medicate my children and say these behavior patterns as a need for more challenging curriculum or responsibility at home. No living with this daily I have had to 'rethink' my position.
The situation is stressful, even with just one. It is important to not lose your cool in front of your son. Be consistent and don't give in to a tantrum. When in a mellow, depressed mood, read to him and do quiet things. Continue to work with your doctor and encourage prayer together and a strong spiritual life. Not understanding can contribute to the problem, but you have already taken the first step. At home visits by a counselor in the home may help.