Feeling tightness & pain under armpit-nerve (?) in armpit feels tight (pulled) compared to other arm which is loose. What would cause this? Already have neck & and arm pain. Treatable conservatively?

Bulging disc. You may have a disc problem in your neck. I recommend a complet exam by a physician. You may also need a x-ray and mri.
Coming from the neck. Disc degenerative disease so called is instability of ligaments that allows the disc to degenerate. Prolotherapy can force those ligaments to heal and get rid of the pain permanent;y/ visit www.Getprolo.Com or www.Aaomed.Org tp find a prolotherapist and learn about this treat, ment.