I had this bad and thought it was just age setting in. In addition to the pain that made a guy's hair stand on end, my finger added the quirk of locking when it was curled, as in drawing a bow! Made for interesting shooting, not knowing if that finger would relax upon release!!!
Between that problem and some Tendonitis in my drawing elbow, I thought I was done shooting bow for good.
Turned out it was inflammation of the tendons the Doc called "Trigger Finger" and a shot of Cortisone fixed it right up. Got the shot about a year ago and haven't had any pain or locking up issues since.
I put up with this for better than a year, when I could have had it cured with a 20 minute visit to the Doc. Talk about dumb!!!!
The moral is don't wait, just go consult with your doctor ASAP and get on the path to painless shooting....