[shipper/receiver for the last 25 years ]

Lots of lifting/reaching? overhead & heavy also?
Might even be repetitive related , combined with your c spine issues.
Any prior whiplash type injuries?

Can you hold your arms up in a firm "stick em up" position and open close hands for 3 minutes or so?
What happens? any pain or heaviness increase? hand turn white when up in air?

Have you had any expert PT or assessments by PT, or DC?
If some of the sx are soft tissue based, sometimes these will be helpful more than MDs mainly looking at a surgical, injections, or Rx fix.