What Causes Bruise And Bump On The Top Of Foot?

I went running yesterday...7 miles. And then later I went back and ran another 5 miles. When I got home I felt some slight pain but ignored it. When I took my sock off there was a bruise and a bump on the top middle part of my foot. Curling my toes makes it painful. Walking on it is slightly painful as well. what could this be.