Sounds like a pinched nerve to me. I would ask that a mri or ct scan be done to have it checked. Pinched nerves can cause permanent damage. How old is your son? Hope he is ok. Best wishes.
Sissie
i am 29, have had that problem for a long time, sometimes it lasts weeks on end...very frustrating and nerve racking. i see a neurologist, and they cant even find a problem..some things are unexplained
The number 1 thing to do is check his blood if you live around woods it may be lyme I had that when I had lyme..