Hi, My Almost 4 Year Old Daughter Has Had A

Hi, My almost 4 year old daughter has had a very large scab like thing on her head since a little before Christmas 2015 - diameter approx. 3-4 inches. It clearly irritates her and also pussing. Her head has an extremely strong bad smell. It smells like a wet dog, which can be smelt if your in the same room - not just close up. She has also developed a rash on her torso (not limbs). She has already had 3 separate courses of antibiotics - all of which made no difference at all! She has been into the hospital at which point they took what looked like a lot of blood and stated they would be testing for leukemia as well as other things (leukemia test came back negative - obviously). Due to how long this has been going on I'm really concerned. Please Help!