Hey man, sounds like we both are on approximately the same injury timeline. I blew up my left AC two winters ago snowboarding. Total Grade III, full tears of all three ligaments that hold the AC joint together. Had about 1.5 cm of separation under x-ray, but no further separation under load (which I guess was lucky). My doc was super disinterested, and just told me I'd be fine without surgery (more on that later). I was lucky that I hurt my shoulder in the offseason, so there wasn't the immediate pressure to ride, but I definitely got back on the bike too soon. I did a lot of rehab with bands and doing wall push-ups, building up slowly over the course of many weeks. It took about ten months before I could do a normal pushup without pain, or bunnyhop a log without feeling a bunch of strain in my shoulder, but it seemed to be healed, even though I had a pretty sizable bump on my clavicle. I rode with an EVS neoprene brace for most of the fall and through snowboard season, and thought I'd got out of it ok this past spring, but on my first mtb ride of the season in April I shoulder checked a tree and hit rewind on all my progress. My shoulder definitely didn't respond as well to the second round of PT, and it was super frustrating. I had decreased range of motion and pain any time I pushed outwards (pushups, holding bars, etc), until randomly one day in the summer I was throwing a suitcase up on a conveyor in the airport and felt a pop. I thought at first that I'd torn everything again, until suddenly I realized that I had more range of motion and no more pain. As best I can figure, that shoulder check moved my clavicle, and then the act of throwing the suitcase popped it back in. Now it feels pretty damn good! Not pre-first-injury good, but pretty damn good. I can do pushups and lift without pain, and my shoulder doesn't bother me riding. Best advice I can give you is to take time off, which sucks, but seriously is the only thing that's going to help, especially being so far removed from the original injury. The collagen matrix that makes up your ligaments takes time to knit itself back together, and if you stress it while it's weak, it just takes longer and longer to heal completely. I'm not sure if your shoulder will respond to PT at this point, but maybe using Kinesio tape or a brace will help give the joint the extra support it needs? Good luck dude.
