I have tingling in my back on or around both shoulder blades more so on the left than on the right. it feels severe and is very uncomfortable, why?

Nerve: If this nerve type discomfort is only a few days old it could be a harbinger of a herpes zoster(shingles) outbreak. Observe for the development of a skin eruption along one side of you upper back. If this develops, confirming the presence of shingles, see your physician as treatment is available. If no rash appears and symptoms persist, a neuropathy is likely. If pain appears, get checked?disk.

Overuse syndrome?: Sometimes too much sitting and computer can cause repetitive use syndrome similar to carpels tunnel and tight mid back pain. Also, too much heavy lifting of weights like kettlebells can cause it through swinging. It's a good idea to have it checked out by a DO physician to do a musculoskeletal exam and get rid of the pain in one treatment. Good luck!