Doctors can tell alot about a skin biopsy, I know this may sound silly to you but anytime I have ever got a rash that itched I use an old timers remedy for curing it works great for ringworm also. cut a limb or leave from a fig tree and there is a white milky substance inside the stem apply that to the rash. it will burn some but it dries it up and has worked for every rash that ever occured in my family.plus its all natural and What could it hurt.