I have a small yellow circle on my big toe that has been painful for a couple days. it is a raised bump that looks very white-yellow in color. ?

Corns and calluses: are thick, hardened layers of skin that develop when your skin tries to protect itself against friction and/or pressure. These usually develop on the soles of the feet and palms of the hands. They can vary in size and shape and are sometimes painful. When to see a doctor: If a corn or callus becomes very painful or inflamed as yours has been.