Upper back pain

I have a pain in my upper back on my left side right by the shoulder blade. By my bra strap. First I thought maybe it was a pimple, but there's nothing there. I had DH check and he said feels like a bad knot in my back. I do workout. Used to workout a lot more and now am getting really back into it that last few days. I use 5 - 8 pound weights a lot for my arms to tone. I must've done something wrong or not stretched enough.
Has this happened to anyone ever? What's the best thing to do. It's not horrible, but more annoying.

Re: Upper back pain

If you have time to fit in a yoga class, it's amazing how it makes you feel afterwards.