Sudden pain in upper back. Sharp severe pain. At what point do I call my doctor. It is around shoulder blade area and is debilitating.

Debilitating = bad. Whenever distress is debilitating and acute is a point to call. Chronic pain is different sadly even if debikitating. Once you know it's nothing new, pain mgmt is all you can expect. But new and bad is worth a call, exam, treatment if possible. Best!