I have a pinching / burning pain on the bottom of my foot. I can t see it myself, even with a mirror. I asked my husband to see what it was. it feels like an area about the size of a dime. my husband said about a month ago, that it just looked like a callous. but now he say it looks black underneath the callous. it has really been pinching an burning much more in the last 2 weeks. My first awareness of it, was last December. i felt a pinch, it felt like a piece of glass or a splinter type jabbing pain, only when i walked barefoot in the house. it wasn t constant...I only felt the pinch in the same spot occasionally. I kept asking my husband to see if it was glass, but he kept saying it just looks like a callus. But now the pain is more constant and burns as well as pinching, and now that he told me it looks black under the skin, i m getting a little nervous. Do you have any idea what this might be? I am 69 yrs. old and in good health. The only medication I take is levothyroxine for hypothyroidism. As far as I know, I do not have diabetes. My internist does blood work 2 times a year, and has not mentioned any sign of diabetes. I m going to call a podiatrist on Monday. Hopefully I can get an appointment quickly.