Hmmmm, is you rash very vivid red with tiny bumps, or it is looking more like darker pigmented areas with lighter areas ? Any peeling ? To be honest candida is a yeast and as far as I know it rarely lives on top of the skin, mostly likes "cavities" and needs a lot of moisture. Perhaps it is not candida (yeast) but true fungus like Tinea so Nystatin in that case is too mild to have an effect. Derm. doctors are notoriously wrong with their assessments *sigh. I always tell my husband that I have no idea how dermatologists and meteorologists exist as a profession at all lol.