Callusing is a build up of dead skin. As the skin dries out, it shrinks. The tension on the skin, as it shrinks, causes the skin to split. This can split into live skin causing pain and at times, bleeding. Using a foot cream with urea can be quite helpful. The higher the urea content, the better. We use 40-50% urea in a cream. If not severe, use a good lotion daily. Dr l.