Sounds like this might be "trigger finger". Does the finger stay down when you open your hand?? There is a simple procedure to repair trigger finger. With just a local shot the doctor cuts a tiny slit in the crease of your palm, then cuts the tube that holds the tendon and releases it. Two stiches later you are good to go.
It will take about 6 months for the tenderness to go away. Mine is still a bit stiff but at lease I have full use of it.
lw
Hello and welcome. It could be arthritis, tendonitis, a dislocation of the joint, related to repetitive motion or any number of things similar. How long has this been going on? what have you used to treat it?
Because it seems to be getting worse instead of better, I would suggest you go to the doctor to have it evaluated.