I Have A Rash On The Inside Of My Knee,

I have a rash on the inside of my knee, sometimes just below and sometimes my stomach that is very itchy. It stays for a week or so then goes away only to come back weeks to a month later. It starts with just an itch but becomes red as I scratch because the itch is terrible. I scratch so much I bleed in spots. It hasn't gotten any bigger from scratching though. It stays mostly on my inside knee.