What Could This Rash Be?

I have this big red rash on my upper inner right thigh and it seems to have spread to some smaller rashes. There's this painful tingling sensation on my leg, but it's not that painful. Then again I know from when I had appendicitis that I don't react to pain as strongly as most people. Also I just got this rash about half a week ago. Is this shingles? I am a college student, and got chickenpox when I was about 5. If it's not shingles what other things could this be? And what ever it is what's the best way to treat it?