I was reading your post and thought I might chime in and give you a though. Have you ever heard of a ganglion cyst? Most of the time they show up on top of a persons wrist but they are also often found on top of ones knuckles. This is very common. It can be very bothersome especially on top of a joint that is constantly in motion. The only sure fire way to remove it is to have it surgically removed because as long as the cyst sack stays intact, the cyst will continue to refill. It's a very easy quick surgery done in office. However, this may not even be what is going on with you. I am a nurse and it sounds like a cyst but this isn't medical advice by no means. Check with your family practitioner or if you don't have one a walk in clinic should be just fine. Also I wanted to mention that ganglion cysts are genetic. Please keep me updated on your condition. I'm very interested. Hope I helped you somewhat.
~ April ~