I’ve had a similar problem on R side …years ago, visits to Dr.John Sarno (now deceased) cut the pain in half…. I still can get spasms, very much helped by osteopathic manipulation and soothed by the Rosen method practitioner….these help manage the pain, with help from heat, Tylenol and occasional pain patch for long days….breathing exercises help a lot, walking, doing stretches/exercises, keeping postures that help make the rib cage more open are part of my management program… wish everyone dealing with this better days and relief !