I am a similar age and have pain in the exact same spot. The differed pain down the left arm is what gave me the most anxiety. Like others here, i have had multiple negative tests and they were all negative.

The thing that relived my anxiety the most (and it took some time) was doing the door stretches. I could feel my muscles stretching in similar places to the pain (even down by the elbow). I decided to stop all pain meds and anti inflams (which seem to have differing results) and just focus on stretching for a few days. It stopped the pain and relieved most of my symptoms. Try stretching gently for extended periods in the morning at night and see if it gives you a similar result.

Thee worst part about costo is the anxiety, i hope you get better soon friend.