I'd get a second and even third opinion - you need an actual working "diagnosis" so you can have treatment options.  If it's yeast - there are some options, if it's some other skin or fungal infection - then you need to know what it is and if it is resistant - someone needs to offer you therapy options or a "plan of treatment."

I'd also recommend things you can do to minimize irritation -

pure cotton towels, clothing especially underwear - use "pure soaps" for washing clothes like the new unscented organic offerings, use cetaphil to wash your body and cetaphil moisturizing lotion -which are products recommended to 'sensitive/eczema" patients.  You might also up the acidopphillus in your diet by having yogurt daily and even trying some probiotic supplements daily.