My Left middle finger knuckle is swollen and there is a hard object that moves around from the top of the knuckle to the right inside. Depending on where this object is the pain worsens. When I flex my knuckle or extend my finger this object moves and sometimes there is a sudden pain and snapping nosie . The swelling subsides and then returns - some times there is very little pain and other times the pain radiates up and down the whole finger. This has been going on for about 3 weeks. Any ideas. I do not remember hitting my finger. I do spend a large portion of my job on my computer key board.