What does she do for a living?
I was a lab tech...lots of manual pipetting (in 70s-90s) on equipment designed for male hands/anatomy, plus computer data entry, with several issues around carpal tunnel, ulnar nerve entrapment(around elbow), and eventually issues could not be resolved with PT or NSAIDs, so in the late 80s I progressed to pain management. I actually had injections through the front of the R side of my neck of lidocaine or xyzlocain and perhaps steroids, into the C3 area, IIIRC. It was Ling ago. Relief lasted for roughly ten or 12 years but as I transitioned jobs and more computer work I has recurring issues that needed PT and all.the work station accommodations the PT could recommend. Lotsa NSAIDs would stave it off but not always. Never bad enough for surgery. Each of us has different levels of pain tolerance too, so she may be genetically predisposed to sense pain more acutely. Now retired I have some minor damage at rotator cuff, and my ball and socket at shoulder are misaligned....probably from birth but tolerated til it wasn't.
If all the structural issues have been investigated (and it sounds like they have) then that leaves something metabolically, perhaps. So family history might matter?