Stress can tighten up those muscles, try massages or buy a hand held one, I use mine all the time and it really helps, I also have fibro, it hurts at first, but once I get rid of the knot I feel so much better.

Sangria, it's a portable electric nerve stimulator. It has gel pads you place on the orgin of your pain. You control the strength of stimulation needed for relief. Mine is the size of transiter radio and battery powered. You can get a script from your MD and buy at a surgical supply store.

Yes I have to get massages every two weeks. Also I freeze a two letter bottle with water and roll it between my shoulder blades lying on my back

I get knots between my shoulder blades too. I also have fibro. I find massage, heating pad or TENS unit helps. Good luck.

TENS UNIT. what's that