I've had a quite similar situation a few years ago when the muscles under the shoulderpads inflamed, it totally suffocated me and i couldn't even walk fast and breath at the same time.
The cause to all this for me was temporary SIBO but a simpler answer is that the liver was overclogged and residuals of the whole mess was a burden for vulnerable muscles and joints.
I guess it can't answer the whole question but i hope it leads you on the right track.