Sounds like you might possibly have some nerve damage in that hand,, & or Arthritis & maybe a circulation problem.
Welcome to my world.
Might as well throw age in there as well.
Playing Bass guitar really helps me with my hands & fingers,, plus an 81mg baby aspirin before I play.
If I didn't play at least a couple of hrs. a week,, I would have at least 3 fingers that will potentially lock up,, ''especially when cold''.
Think the majority of it is from pulling on wrenches most my life,, plus throw in some bike wrecks, frost bite,, & a few other things ….