Thank you all for your responses. I really appreciate it and apologize for the tardiness here. It's been hard for me to get online except from my phone and this site is not readable from the phone.

Lara: We haven't done playdates. Part is how busy we are with the kids. ; part because most moms I know outside of work are SAH and don't want to do anything weekends; part because we're exhausted. I just don't even know how to do that or who to reach out to. He won't say any of his classmates names and he says he has no friends there. (Okay, yes I know this is a copout answer and I feel stupid, but I can't make friends for myself -- I have no idea how one builds relationships.)

DEG: Thanks for the recommendations; I have one Yoga video we like to do, but could use more and breathing would be good! I like doing this with the kids on a cooped up day. (http://www.amazon.com/Storyland-Yoga-Kids-Families-ages)

I'd heard of selective mutism but don't know too much about it; Mazie -- will be PMing you for more information. I'll ask his teachers if they've had kids with it as well and if it feels right, will followup with his doctor.

Again, appreciate all the responses. Will follow up when I have more.