I think you should call your doctor...wondering if it could be gallbladder related?
Does it radiate upward?
I've had pinched nerve/compression in that area, and breathing definitely made it feel worse. But I'd not put no appetite or feeling freezing cold with a pinched nerve.
I had one gallbladder attach, and for sure it was under the shoulder blade.
I also have had a collapsed lung and the surgery, so that pain was also similar (except without the feeling of an elephant on my chest).
Please call your doctor and get checked out anyway.
q