Could this be skin cancer or a harmless mole? (Photo)

I have had a mole on the back of my upper thigh since I was young. It is all one color, it has defined edges and is the size of a pencil eraser. For the last month it has become painful when sitting or rubbing up against clothing and is dry and scaly. The best way for me to describe it is irritated. I am a 22 year old female. I'm afraid this could be skin cancer. Any suggestions? Photo is attached.