How long ago was your surgery?
Has any new imaging or testing been done yet?

The problem could be from the stump rubbing or still causing compression, internal scarring, scalenes, or pec minor. possible some myofascial sx too.

I know in the past a few did have to go back for total rib removal, cleaning up of scar tissue, and /or pec minor or more scalenes..
thorough testing & expert TOS doc will be best way to go...to find the best treatments.

but just guessing - that partial rib might be the troublemaker...