Suggest Treatment For Rashes On Buttocks

I have this rash on my buttocks, my gyno said that it was a yeast infection and she prescribed me Nystop. I haven't used the medication as I should have. My question is can yeast infection cause boils? I have been getting boils on my buttocks. They keep on reoccuring. I told my gyno about this and she gave me an antibiotic, which worked for the meantime but the boils are reoccuring again. My next question is, what is my next step?