Yes, it happened. It is different from what I thought. I had a bad ski accident a few years ago and dislocated my left shoulder. This impingement happened as a result of instable/unstable shoulder. Shoulder is the most wonderous joint of your body. It is held in space perfectly balanced to provide amazing degree of freedom.
I thought it is like normal shoulder pain I know. Now I know shoulder impingement is result of over-use and inflamed tendons and such. It is more like random pain here and there as the nerve gets pinched. It feels like burning, hot, upper arm, in the elbow, in the fingers. It is strange kind of pain where you can't pin point.
I did V5 and dyno on left hand reaching overhead. I put my weight on that shoulder after wide gaston. Well, it felt weird and I sat nursing it.
That night, I have this pain in the socket and elbow. I had shoulder pain before but this is different. It is like hot wire running through my arm. Shortening this story, after a visit to an orthopedic doctor and two shots of cortisone on my left shoulder. They give these shots as a way to prevent further nerve damage. There are two basic problems. One, those shots hurt for two days, just mild pain but present. Two, the shoulder is doing its own thing to settle back. On the third day, it feels good. I am doing rehab exercises.
Climbing wise, I know is that I am doing something wrong. I put too much stresses on same joints in same fashion repeatedly. The big question is how to recycle things; hands, feet, arms and shoulders. My trouble is I keep the same grips instead of switching and using different positions including getting used to utilize as little force as possible.
Spread tension; body tension but it means positioning one's body to reduce stress on feet and hands same way over and over again.
Rehabilitation! I am doing scapular stabilization first and doing no weight ROM exercises. ROM stands for Range Of Movement. Without using weight, one needs to stretch these tiny muscles and maintain or increase ROM. Once, I am warmed up and I am exercising general opposing muscles.
One thing one needs to be careful with is to exercise these shoulder muscles, one needs not to exceed 2 or 3 pounds weight. It is better to do free weight than elastic.
Despite of opposing muscle training, I neglected pectoral muscles and MD Peter Re of the Sports Medicine, the good doctor mentioned about my shoulder curvature. I suppose it tightens and makes you prone to shoulder problems. I remember pain around scapula, aka shoulder blade a few weeks ago. Listening to one's pain is an art.
Check this gem of Climbing.com article by Griffith.