I wish I could give you a hug too!
Question per the screaming--- have you looked at OT? I know one of my DDs did well post OT and we still implement some of the techniques our OTs used. DD had a dx of PDD-NOS and SPD. She would get overstimulated/overwhelmed/stressed out and simply shut down which appeared as hearing loss (it is not). OT helped a lot.
DD had no changes in behavior with diet restrictions.
A lot of kiddos do OT and meds combination. As a PP said, if meds dont work you can stop taking them or try a different med. Watch for side-effects and start low. There is nothing saying that he will always have to take them or take a certain med, etc.
Also, as a Spec.Education teacher I have seen meds change kids lives for the better. Which is why I chimed in. Yes, diet works for some. Yes, behavior therapy works for others. and Yes, meds work for still others. Or a combination of the above. There is no 'right' solution for each kiddo. You have to do what is best for your individual situation.
Violent behaviors can be frustrating to everyone-- the kiddos included. Long-term issues can affect self-esteem and relationships. I would definitely try a trusted Dr. suggestions that would make your DS and your family's quality of life better. Also know that if something does not work (diet, behavior mod, meds, etc) to try something new. So may people are against one thing or another due to personal opinions or circumstances, but honestly every family will take different routes to helping their child in the best way they can. Also over the years or as a child gets older a new approach may be needed and that is OK.
As a family, everyone tries to do what is best for their kids, their family, their own peace of mind, at that time.
Keep us posted and I hope you, your family, and your DS find something that helps soon!!