For what it’s worth, something similar has happened to me on three occasions, all at night in bed. It was like a fist had formed in my upper back and was turning and tightening and making breathing very difficult and painful, and pain radiated into my chest and upper arms. The first time I rushed in a panic to emergency and had the heart work done, etc., but all the tests were fine. The second time I tried to relax and figure out my pain and breathlessness, consulted online, came upon the concept of cramping in the diaphragm. There were suggested breathing exercises that calmed down my cramping and breathing fairly quickly, and I knew what to do the third time it happened. It’s always nice to turn fear and uncertainty into a practical remedy. Just something you might consider, and I hope your issue is as simple as this.