What Could The Bruising In Foot Refer To?

a few days ago my foot was bruised for no apparent reason and finally the pain went away. but tonight i was walking around and all of a sudden it felt as if something was stuck to the bottom of my food (on the pads) and i looked at it and it was a raised puff. it looks as if two silver dollars molded together and are on the pads of my food. what is this??