I got something similar next to one of the joints of my middle finger during my second round of HW (was an extra strength version). It was like a hard knot. I've wondered if it was gout, though I'm young for it, a bone spur, or if the HW did maybe send a parasite there or maybe one was there and died there. It seemed to appear almost overnight. I kinda have thought not gout, because at the same time as this appeared, I was having other sore joints in my other fingers/hands. However, I'm thinking the timing of it turning up when I was taking HW was probably just a big coincidence. (Been off of the HW now for about a month.) If it was a parasite, I expect the finger will be getting better over time as the body breaks it down—I am pretty sure whatever it is, it's not alive now.
May just be the onset of a type of arthritis, but I'm hoping not. The knot is about 1/4 inch across, and you can see it. If I wind up doing a lot of typing or mouse-work at the computer, I may get some swelling, but most of the time there isn't any. I feel another similar knot, just much smaller on another finger. I plan on asking my doc about it when I go in August, if it's not gone then. If I find out something, I'll let you know. I bet for me it's probably some sort of arthritis; I'm 39, but "Arthur" doesn't discriminate. There's more than 100 varieties of arthritis out there, so with my "luck" I may just be stuck with a fast acting one. Would be a real bummer. When it's painful, it's hard to do my job and is almost impossible to type or use the mouse.