Suggest Remedy For Extremely Itchy Rash On Groin Spreading Very Fast

I am 15 years old and have been sexually Active in the past but not in the past 3 months. Recently I have noticed a rash on my groin and pubic area spreading pretty fast. At first it was just itchy now the skin at my groin is very red, gets extremely itchy and now is very very flaky and the skin looks some what wrinkled. It is spreading slowly over my pubic hair area and I'm too embarrassed to see a doctor or tell my mum. Please help.