re: Shoulder pain. What’s the deal?

What about this issue for chest pain. For a few weeks now I've had pain when I do flat bench. I'm fine through warm up and then when I hit 135 I have pain in my pec below my left armpit maybe an inch or two below where my pec hits my shoulder. It's only sharp temporary pain. I can lift through it, but it hurts. As soon as I'm done with a set I'm back to normal. It doesn't hurt when i stretch or swing my arms after the set. I have noticed it when doing dips and chins, but not as sharp. It doesn't seem to bother me when I do incline and no pain at all when doing overhead press. I took 3 days off then tried yesterday and it was still there.