Incredibly painful left shoulder blade. Hurts to move neck. Worse at night, feels like arm is being ripped off. Ideas about what to?

Rotator cuff injury? If the shoulder blade pain is "inside" toward mid back, then likely muscle spasm. If the pain is "outside" toward the shoulder & going down the arm, then may be a type of nerve pain. If you sleep with elbow up under your head, then may be rotator cuff injury. You must sleep with elbow down - below chest level. If that doesn't help and the pain persists, then do see your medical provider.