I had a similar experience getting out of the military. I had a known back injury, but nobody could tell why it was manifesting the way it was. I eventually ended up at a sleep doctor because I refused to be put on opioids but could not sleep. I was put on Gabapentin, or rather over-dosed as this use was off-label. The physical therapist noticed a change in my range, and that my back could suddenly "pop" and release tension. Three years later a chiropractor discovered the source of my sciatic nerve pain: a fractured disk that had healed over my sciatic nerve that caused all the rest of my muscles to tense up. My life is mostly normal now that I have some tools to cope with the discomfort when it creeps up, allowing me to head off any potential pain.

I guess my point in sharing this is that nerve pain can be very hard for doctors to diagnose, much less treat, but don't give up.