Many thanks for all you suggestions. I have seen a specialist, as well as my own doc, who is a DO, and have had the limit (3) cortisone injections in the ring finger. I guess it's a return trip to the hand doc to look into surgery. My work is all of those bad things (repetitive, vibration, etc) which I ameliorate as best I can by using padding, gloves, ambidextrous training, etc.
Guitar stretching is good - I'd forgotten about that, which is pretty silly considering one of the things I build is acoustics... I used to have a site bookmarked with "yoga for guitarists" similar to this:
https://guitarlessons365.com/essential-hand-stretches-for-guitarists/...