I developed a left shoulder impingement a couple of years ago that I believe came from poor posture/rounded shoulders. I've been working very hard the past two years on a "shoulders back" posture improvement, and I think it's worked. I have zero pain in that shoulder now.
Unfortunately, and this is just self-diagnosis, my posture changes have now given me distal bicep tendon tendinitis. I came down with it in January of this past year while I was doing absolutely nothing. No golf, no kayaking, nothing. That's why I'm speculating it has to do with my postural changes. Like maybe it's being stretched more than it's used to. So now my left shoulder is better, but my left elbow is bad. And after 10 months, I guess it's just not going to go away on its own.
I have some quality curcumin on the way which I tried before without success, but this is a different kind. I'm not optimistic, but it's worth a try. I'll also add carnitine to the list as the next step as I've been meaning to try it anyway.
If I'm right about what caused this, I think stretching might help too, and I'm going to get on a strict regimen.