Chiropractor, Ribs out of place is VERY painful but can be dealt with. Also a spine with slight twist puts the ribs under pressure. That is also very painful. A modern trained Physiotherapists can also deal with it. It may not be this at all but I thought I'd offer up this idea to add another possible avenue to peruse in your search for the actual cause.

I hope you find what the actual cause is and find the right medical/health professional to deal with it.

My brain is just a toy box filled with weird things