Has he gotten any MRIs and Xrays to check for serious spinal/bone/disk problems?

Maybe a chiropractor? or Osteopathic dr ?

If it is a muscle based pain and not a vertebra or disk problem, physical therapy and some expert chiropractic should be helpful.

It is hard to suggest things without more information.

when did pain start?
What may have caused the pain?
info from MRI or Xrays?