I periodically get a sharp pain between my shoulder blades. At its worst, it's not just hard to turn…

I periodically get a sharp pain between my shoulder blades. At its worst, it's not just hard to turn over, but even breathing hurts. The pain can also radiate forward. The intense pain subsides in a few minutes, and then it's bearable. This doesn't happen every time, but it's happened at least three times in the last month. What could this be? 😕