Thanks everyone for your support.

Day 2 went well, too. We started swimming. He loved it and is already looking forward to next week. He was hanging around me today afterwards too so it already feels like it's paying off and helping to improve our relationship.

DH noticed him do the 'shutdown' today when we had friends with kids over and they were playing in the yard. DS got overwhelmed with an activity they were doing, and just stood there staring blankly (the other kids are quite boisterous compared to our DS who is more of a quiet one). This shut down thing has really got us worried. Is it just his age and the fact that he doesn't yet have well-develpped coping skills and social skills? Can we teach him not to do it or arm him with skills to cope better? We're worried that if he doesn't stop doing this he'll get crucified at school.