Immense pain on back around left shoulder blade can barely move my arm. neck in pain too 32 y/o f. i exercise frequently - run- lift -yoga what is it?

Strain probable: It sounds like you've strained your shoulder. I would advise heat or ice, off and on, and gentle stretching. Perhaps an anti-inflammatory like Ibuprofen (advil, etc.) or Acetaminophen (tylenol.) hold off on the lifting and yoga until the pain lightens up. You sound pretty tuned into your body, so go to a medical practitioner if this doesn't lighten up fairly soon, like in a few days.

Pinched nerve: Most commonly, non traumatic shoulder blade region pain is actually referred pain from your neck. This is commonly known as a pinched nerve and can be from a disc bulge or herniation as well as other cervical pathology. See your doctor to find out for sure. Mri often needed.