What Causes A Rash On Elbow And Under Breast Along With Itching?

First symtoms were red, itchy bumps under my arms. Then 'sunburn' on neck and chest without being in the sun - very itchy. Then visable rash on inside of elbow and under one breast. Went to doctor, said it's yeast fungus. Very itchy last night. Is that all it is? One dose pill doesn't seem to be working.