Random flashes of pain - Did I really overtrain ALL muscles from shoulders to hands??

Hi Dr 8a and everybody else, short backstory: I got back into proper climbing last year after a long-ish break of roughly two years. After the usual slow start I actually got into rather good shape again and started bouldering in January. About three weeks ago I must have done a little too much, my left arm (mostly biceps/triceps) hurt for a few days as if it had been hit by a blunt, large object - hard to describe but it was kinda like after falling on the arm, there was not one single center of pain but the whole arm hurt basically, in a very blunt way (sorry, don't know a better word in English). I rested a few days, tried easy climbing, but then rested again since it did not feel 100% good. Then I tried again when I thought it was over but yet again, my arms (this time both of them) feel weird. It's not a bad pain this time, and also not constant. But it can hit me while lying in bed, or sitting in the office. It's like tiny flashes of pain in random spots of my forarm, biceps, triceps, shoulder .... it feels like a muscle thing, not like tendons. Last climbing was a week ago since then I haven't done any exercises but still it's not really improving, just lingering. Right now I can feel it in my deltoids (posterior) for example. Sometimes it's okay for several hours, then it suddenly comes back without any obvious trigger. Any idea what this is? Simply overtraining requiring some good rest? Do you think I should stretch? Or even do some (really) easy climbing - I've a had a few arm issues in the past that only got better through climbing, not through extended rest. What surprises me is that it's not only one certain region but rather both entire arms seem to be affected .... although the areas where the pain appears most often are triceps and brachioradialis. Thanks!