I've had a kidney-shaped sore near the center of my right foot for almost a year. The symptoms and appearance of this sore vary, but never stay the same for more than a week or. Sometimes it causes an unbearable itch that won't go away no matter how much I itch it. Often it appears as a dry, tough patch of (callus-like) skin with a line of red inflamation around it. But, the sore has also turned into a blister with fluid inside of it? Sometimes it is extremely painful (but not nessarily itchy) when I touch it, and other times there are no symptoms at all. However, it never completely goes away.
Any thoughts or potential diagnosis are welcome. Thank you!