Suggest Treatment For Pain On The Knuckles

I ve been having trouble bending my left thumb from the knucle for the last few months. I am right handed. It doesn t hurt but it s effecting my ability to graps items tightly. I can bend it with assistance from my other hand without any pain but it pops right back upright. There have been a few occasions when, during normal activity, my thumb seems to get stuck and then pops (I can hear the pop) back into a relaxed position.