I have learned the hard way too. I've had a similar problem for several months. For me the pain is at the back of the shoulder, near the acromion. The doctor thought it was a small labrum tear. I went to rehab and discovered that many of my stabilizer muscles were weak: external rotators, lower trapezius (which needs to be strong to allow the shoulder to open up completely), and serratus (I have some winging of the scapulae). They say I have naturally loose joints, and combining that with weak stabilizers is a recipe for injury (especially when you push yourself too hard like I did).
I too can pop my shoulder "to make it feel better" (I used to do this by holding my arm out to the side and internally rotating until it popped), but as with you it felt like something that I shouldn't be doing. I have stopped popping it since I read your comment, and it feels better.




