Don’t give up! I know how hard this is and have been there. I recommend bodywork as it can really help his body start to regulate. The best site for this is http://www.moveplaythrive.com. This was started by Sonia Story who had 2 daughters with major sensory processing issues. There are online classes taught very clearly about massage and bodywork tools that you can do to start helping your child’s body. They really work but need to be done daily for quite awhile–if you do them though as a routine they will make a lasting difference.
I especially love the Rhythmic Movements that she teaches (based on a book called Movements that Heal). Also there is one other bodywork tool at http://www.qst.org that you can add as well. You can also look for a practitioner in your area.
Then add some nutritional supplements and diet changes (www.mychildwillthrive) or find a MAPS trained doctor in your area.
Take good care of yourself and start to add these things in one day at a time. It can be overwhelming but it’s worth digging in to deeper solutions for your child then just medication (which treats more symptoms, less the underlying cause). No judgement towards medication, but in my experience with a very affected explosive ADHD/oppositional 5 yo boy (who is now a mostly normal functioning 11 yo) it took the deeper solutions to make a true change. He is medication free and it took a lot of bodywork and reading on my part. I had to rest a lot and cry at times too. But I never gave up and I kept reading and working to heal his body & sensory processing system. Take care!