If you haven't thus far, I recommend reading Growing An In Sync Child. It's loaded with sensory activities you can do at home. The most important thing we learned three months ago when our daughter was diagnosed with SPD was about "heavy work." For example, move a pile of books form point A to point B; fill a box with something heavy and push and pull around the house; carry laundry; pull on a resistance band. If you can put him on a schedule of activities that involve pushing and pulling on his joints, I believe it will help with his disposition and behavior. Most of us are in the same situation as you, so let us know when you need support. Welcome!