I've been climbing 30 years and my posture is shit. Just recently my elbows fully packed in and really started hurting. All the time.
Normal elbow eccentric exercises made it worse.
I have worked out that my elbow pain is caused by nerve entrapment due to poor posture but I'm now well on the mend after much time googlin and youtubin.
Here's a video I made which might help those I the same boat.