Yeah same with me. I’ve had wrist tendonitis but no finger issues.
Sounds like you may have a string or a fret with a shard of sharp metal, @tamaraster?
If it’s the strings, the solution is easy - just change them. If it’s a fret, personally I would file it off and polish it with high grit (2000+) sandpaper, but you may want to have a pro do that. I’m not a pro but I have experience polishing metal, which is the only reason I would do it myself.