I have noticed a small cirlular mark on the inside of my left thigh,just above the knee.It doesnt hurt or itch in any way,and you cant feel it by running your fingers over it,as it appears to be below the surface of the skin.It is red in color,shaped exactly like a ring,but i have no memory of having bumped into or knocked against anything lately.Its been there for two days now,and i was just wondering what it was.