I had that some years back..or something similar.
Played hell w/ several docs to find the culprit.. was through MRI's, X-rays, and finally a hand specialist worth his salt hit the nail.
I had what they called "trigger finger". There are tiny hanger brackets along the finger where the tendon rides through what he described like fishing rod "guides". Those got inflamed and then the tendon wouldn't go through and it hurt like I got hit with a cattle prod!
He said if you screw around and tear loose the li'l brackets that hold the "rod guides" in place, it's MAJOR surgery to repair them!
Don't screw around with GP's (No offense docs) but see a bona fide hand specialist NOW!
Few shots of corteson in the RIGHT spot(s) and limited activity, ice and then therapy and it was ok.
I shot 2 under (mine was the ring finger) for 2 years till it was ok to use again.
...and no, I'm not a real doc, just play one on the internet...see a Specialist!