M.K.
I agree, talk to the doc about a Physical Therapy referral; he probably would not need to go long, but the PT would be able to give you some great ideas to get him up and moving. Beaumont has a great pediatric facility in Royal Oak; there is also Childrens who has satellites all over. I would go wherever the PT could see him the fastest - even if it wasn't a pediatric facility.
It is also good to see if you can get him engaged in various play activities with the other kids and see if distracting him would help.