I have this among back, neck, stomach, head, arm spasms. It stems from my spinal and spasms outwards. Maybe he has spinal myoclonus like me- it is absolutely horrible! Spinal Myoclonus is spasms of the spine. My gets worse all the time. I have had it for 7 years Ask your nuerologist to give him an MRI, EEG, CAT Scan etc. Good luck. Also you might want to have him try a Chinese accupuncturist I go 2x a week for 2 years. It is very painful but it did help a little- now it doesn't help but I am so desparate that I still go. (Mine spasms really hurt so not sure if he has the same thing but hopefully that gives you some direction.)
Chronic back pain without definite findings of abnormalities on diagnostic testing is very difficult to assess and treat. I can appreciate your frustration as it would be easier to correct if a specific cause could be identified.
I don't know how long your husband has been in constant pain or the type of tests that he has had done. The fact that "numerous doctors" have been consulted without success makes his situation even more complex.
No medical doctors contribute to this forum and assistance and support is provided by members who are or have had similar problems.
Has there been a referral to a pain management specialist? Without any pathology identified, the goal is to obtain maximum pain control while maintaining optimal function and movement. Have any neuropathic pain relievers been tried? (Lyrica is an example)
Managing pain may be his best option at this time.
Post with an update and any additional questions/concerns you may have.
Best wishes ----