My issue definitely involved levator scap and upper trap. I spent most of my free time on a computer and my job was doing repetitive motions out in front of my body 8 hours a day. I have terrible posture and forward head. My issue started with pain in the armpit... Then came scapular instability. My scap stability is improving albeit slowly. Basically the pec minor, upper trap, and levator scap were working over time for my job doing the motions out in front of me.

Once they overpowered my back muscles enough my shoulder basically got stuck in that forward position and my shoulder blade had an anterior tilt. This causes all kinds of popping and grinding noises..I know if I can get that shoulder blade to sit back and fix my posture that my symptoms will resolve. It's just incredibly frustrating when you have a few good days and then a really bad one that sets you back.