My first cham had something similar to this. Sorry i cant remember exact what the vet called it but he said it was from a fracture. (He had a special name for the fracture).
l had a panther that had the same thing. Turned out that it was caused by an infection. The bump was basically hardened puss that had attached to his ankle. I didn't even notice it until one day he wasn't using that leg like normal. I had to inject Ceftiofur subcutaneously (just under the skin) into his back legs over the course of a week. The infection greatly decreased in size during that week and he now uses his leg like normal again. I am not saying that this is the case, but a possibility. You may want to consult a vet.
What was the timeframe for this showing up? More history please .
Trauma? Sprain? Broken bones?
If it was a few days, I'd think more along the lines of an infection.
Gout deposits usually have a different look, feel and location and take longer to form. If the area is as hard as a rock then that is still a possibility. Gout also tends to be evenly distributed among all four feet as well as other areas.
Yes, it happened within last 7-8 days I guess. It became really noticeable to me only today. From what you say, it sounds like an infection.
I better go to a vet to get confirmation. Many thanks.