I feel your pain as my eldest has ADD. After 2 years of the struggling, fighting, crying, unexpected outbursts and getting nowhere with school, we adjusted ds's diet to include lots of protein and all natural foods (no HFCS, dyes, etc) coupled with extra Omega 3s and Source Natural's Attentive Child (magnesium and zinc supplement); it helped for a while. About 3 months ago, after it getting to the point where he was barely able to function despite all these changes, we made an appointment with his pediatrician. He's been taking 25 mg of Strattera since then, and I have my son back. There are still days where he struggles a bit (if he doesn't get enough protein for breakfast or he's overtired), but it is nowhere near what we went through before. We are all happier, and I am so grateful.
One of the books I read recently said that the parents of an ADD/ADHD child basically have to be the frontal lobes of their child's brain until they are adults... that's hard enough for our own brains to do sometimes, nevermind taking on someone else's!
This is not to tell you to go medicate your son, rather just to share our experience and to let you know that I understand. I will pray for your days to become calmer and for him to focus better. :grouphug:
eta - As treestarfae says, lots of exercise does help.