Terminology in the sticky thread- Medical Dictionary & MRI/CT Terminology
might explore all sticky thread at top of each forum you find of interest..

I had delayed pain with my RSI/TOS injury so I know how difficult that is to describe to drs, when you may not be hurting as much at the time of the appts..
Did you have a whiplash effect from the accident?
TOS can happen sometimes after whiplash incident..

That might explain the headaches, cracking neck , tingly hands and even tilted sitting , there is some related co factors..
The c1 c2, whiplash/neck trauma , soft tissue, strains, trigger points , then the other spinal issues also..
Have you had any PT ? advanced or generic .. some are better than others..

You might consider some sticky threads on our TOS forum too..see if it sounds familiar -
https://www.neurotalk.org/forum24/