What Causes Persistent Pain In The Left Arm Pit Radiating Towards Elbow?

A couple days ago (3-4) I woke up with this weird pain that extended from my left armpit through in between my arm muscles (inner arm, pretty much in between my bicep and tricep). Didn t think much of it other than probably sleeping on my arm. Later that day I went to the climbing gym. And when I was about to dynamically warm up on a climbing problem, I raised my left and this weird pain extended from my armpit to halfway to my elbow in my inside arm. I thought that maybe that some muscles might be sore from climbing 2 days before, which would have been very odd but I couldn t think of any other reason. So i tried stretching it, which both hurt and didn t help. So after climbing for 30 mins I decided I couldn t get a good workout in, so I left. Its been about 3-4 days and the pain is still there, and I ve tried massaging it a bit though it hurt and stretching more which also hurt. And last night while in bed I decided to compare if there were any differences in between arms. So I was feeling the spot from where the most pain starts (Right in my aempire and follow it down my arm). I noticed a vein/tendon or something, that wasn t present in my right side. I kinda freaked out a bit because as a climber one of the most common injuries is a popped pulley in your fingers or potentially down the forearm, which is when a tendon pops out of place and the ligament is either slightly damaged or fully torn. I thought maybe I could have done something similar in my armpit/inside arm area. But from slightly pulling my index finger pulleys I remember that certain movements were unbearable, but now some movements such as raising my arm is pretty uncomfortable and relatively painful but there aren t any unbearable movements, although this might be because of the other muscles and tendons involved vs the finger tendons/ligament being so specific. I m just looking for some potential explanation because there were rock climbing tryouts this coming weekend but this hasn t gotten better, so I don t think I can perform at even 80% of my potential, which is a huge bummer. But I d like some recommendations or thoughts. Thank you