Chronic shoulder ache (post PT for impingement)

Over a year ago I was having pain typical of shoulder impingement, and started physical therapy after 3 cortisone injections failed to provide lasting relief. The PT provided significant relief and although I didn’t recover 100% range of motion I was thrilled. I stopped going to PT but did continue doing some of the exercises at home (perhaps not the right ones or I limited them too much?). The pain returned but is very different. It’s always been more of a dull ache and feeling that something is wrong than actual sharp pain, but before I could occasionally sense a concentration of pain in the front near the acromial gland. Now the source of discomfort seems to be closer to the shoulder blade which often feels like it’s sticking out improperly (the mirror says otherwise), or that the shoulder is “hanging down” out of the socket slightly as if the ligaments aren’t holding it in place as tightly as my right shoulder. It feels slightly better propped up, but even in bed lying on my back (the ONLY position the shoulder can tolerate) it feels a little “off”.
When I was a kid, I used to perform a parlor trick where I’d clasp my hands together behind my back and then rotate them over my head without unclasping, pulling one shoulder slightly out of the socket in the process. It caused me no pain and I remember doing this for my classmates as early as first grade and as late as seventh. If this made my shoulder unstable (or exacerbated an existing instability), what can I do now to treat it and hopefully get rid of this constant but low-level pain.