Has your husband gone to an osteopath or physiatrist (physical medicine doc)?

Osteopaths have the same training as M.D.'s, but have additional training in muscular/soft tissue manipulation and other gentle modalities.
Physical medicine docs (physiatrists) specialize in physical medicine and rehabilitation, focusing on diagnosing and treating conditions that affect mobility and function, such as pain, injuries, and disabilities. They develop personalized treatment plans that often include nonsurgical options.

I hope your husband can find some help.

Chiara