I had a pretty bad accident and quit riding because of pain in my shoulder muscles & nerves. 9 years later I found out I had stress fractured 2 verts in my neck.......lots of pain. I would recommend he get with a sports medicine MD who has lots of experience in setting people up on re-hab physical therapy programs and get on with it. Then trade the Dyna for a RK or EG and get a suspension upgrade to soften the ride further.