Sudden sharp shooting pain just below my left shoulder blade and a little lower down my back. it hurts to breathe deeply or move certain ways. i have hashimotos disease and am hypothyroid. i haven't had a back injury. any insight into possibilities?

Costovertebral: It's possible that your strained your costovertebral joint/s (where your ribs meet your spine). Usually this resolves spontaneously, but can hurt with deep breathing and movement. If it doesn't improve in a few days, please see your PCP for evaluation.

Pain shoulder blade: Yes but need more information such as have you any other illnesses or do you take any medicines? Wha have you been doing just before the pain started. Happy to do 2nd Opinion for better insight.