I am borderline TOS/chronic RSI, w/past whiplash, past concussion, RSI shoulder strains.. hyper mobile... but all standard testing comes up negative.. according to general main stream MDs...

My chiro & a PT professor did more in depth & more hands on evaluations and they agreed. Most Drs don't really do that hands on, if imaging or standard test don't show it they don't look deeper..
I do have the white hand when arms are up and flushing red when lowered, plus the trigger points, muscle spasms, and a raised & stuck top rib from extreme muscle spasms- that was greatly reduced by the PT professor with a top rib mobilization.. I related that to chiro and he followed up when needed..
My chiro had a low level laser (aka cold or soft laser) that was awesome for pain relief..might be worth exploring that topic.

So you could be in a similar situation, not severe enough to warrant TOS experts or deep testing, usually those are for pre surgical cases/severe pain.. but the proper PT and gentle stretching & posture can be very beneficial..

You certainly don't want to risk getting into the severe stage...if it is a mild version now. Explore the RSD/CRPS sticky threads too if you haven't yet..