I’ve had shoulder/thoracic muscle spasms that travel the whole side from neck to bottom of ribcage. I, like you, tried many different approaches. I have the muscle relaxants and pain meds, which I don’t like , but at a certain point I take, to get some sleep. I FINALLY decided to try acupuncture. No more muscle spasms, except on occasion if I do too much with my right arm, then all Hell breaks loose. I’ve been having acupuncture treatments for 2 yrs this month. I’m on a maintenance plan. My acupuncture Doctor has helped me tremendously. Acupuncture may be worth a try. Have you tried chiropractic? I’d had a mastectomy and she feels this is scar tissue. Blessings and I hope you find some relief.