Like lot's of the posts have suggested, best thing is to get it checked out. Probably first stop would be Sports Medicine clinic, while bass playing isn't necessarily a sport it can be strenuous and that pain could be muscle, spine, or nerve related. Orthopedic surgeons specialize in different areas, the Sport medicine clinics usually have the whole spectrum. I worked 20 years + as a heavy equipment mechanic and did some damage over the years, not to mention, car accidents, motorcycles, and basic dumb stuff with a lot of guitar playing. I found I was having pain and losing strength in my right arm with numbness it ended up being my neck. About 10 years ago I had a fall that separated my right shoulder, the MRI showed that the rotator cuff and bicep were also damaged. Moral of the story I found good doctors, had the shoulder repaired and eventually my neck fused all about 8 -10 years ago. I'm 64 and I played a 2.5 hr gig two weeks ago. Make sure to find doctors with referrals and get a second opinion if surgery is recommended. Good luck with it... no reason to play with pain. Might only need PT. I do try to get to the gym at least a few days a week.
