Your symptoms sound very much like my husband’s situation. Two years ago he developed burning in his stomach and this feeling of tightening or muscle spasms in his stomach/chest area. An endoscopy showed an ulcerated area in his stomach from daily aspirin and evidence of a hiatal hernia.
His stomach has now healed. However the spasms, which felt like a band pulling around his ribs or a gripping feeling in his stomach area, persisted. They were relieved somewhat by taking FDgard. It’s an over the counter med recommended by his gastroenterologist. It’s safe to use as it’s basically oil of peppermint. It seems to be a common med suggested for people with a hiatal hernia.

Because the symptoms didn’t go away completely, his gastro-doctor also prescribed a very low dose of an anti-anxiety med, Zoloft. He’s not prone to anxiety but the med works as a relaxant for those muscles. 100mg of Zoloft brought significant relief. Added to that was 5mg morning and night of Buspirone. That was the winner long term. 100% of his symptoms are gone.
Although his doctors didn’t suspect a heart issue, prior to going on those meds, my husband had a calcium score test run and a physical to rule out any heart issues.
I hope this might help you or give you a direction to follow.
Have you had a physical to rule out any heart/lung involvement?

I have had this same condition for over 4 years now and it's getting worse. It is constant and the most relief that I get is when I'm laying in bed on my side, but even then I am aware of it. I also have an unrepaired hiatal hernia which was discovered during an endoscopy about 3 years ago but they just give me Omeprazole for it and, of course, it does nothing. My pulmonary doctor says it's not my COPD but thinks that it has to do with pinched or damaged nerves in my rib cage but X-rays have not been much help although they did show some deterioration in that area of my spine that might relate to my condition - nothing definite was discovered. Still, nothing is being done. I, like you, can hardly take it anymore. I'm 77 but still would like to find some answers. There's all this diagnostic equipment but what good has it done me - none! Have you, since you post of June 10, 2022 discovered anything new or relevant to our conditions? Thank you!