How Can A Fungal Infection With Dry Skin With Itching Be Treated?

I am suffering from a fungal infection in my groin area where there are red patches. Sometimes after taking a shower it looks smooth and shiny but then when I get all dried up it starts drying up. And at night it starts peeling off by itself. when i peel of the skin peeling, it grows back the next day and when it itches and I scratch it, the skin also peels off. my doctor gave me gris-peg and this one shampoo with nizoral in it. but it doesn't seem to be working. I've been taking and using it for 2 weeks now. what should i do?