Sounds vaguely similar to something I had. My left index finger swelled up to about three times its normal size between the lower two knuckles, and was extremel

Sounds vaguely similar to something I had. My left index finger swelled up to about three times its normal size between the lower two knuckles, and was extremely painful to the touch (going through your A-levels whilst on 60mg codeine four times a day is an interesting experience!). No trauma, it just happened for no discernible reason. Various doctors had no idea what it was, and it was still like that some months later, so I ended up having exploratory surgery on it. Turns out it was just a fluid-filled sac of some sort - nothing particularly unusual, and not really any sort of growth, it was just there and shouldn't have been. It has never reoccurred. Side note: general anesthetics are _weird_. I have memories from during the operation of me looking on that feel 100% real, but they _can't_ be (the room had no walls for a start, and I'm looking at myself in the third person).