What Causes Rash Inside Groin Area?

I have a rash in the side of groin area where well above the anal area. It has become progressively large and kind of hard. It is very itchy. I have had this type of rash come and go for several years in different parts in the same area. I have used hydrocortisone cream to tame the itch. What could this be. Tried to search on the internet but do not know what it is. I need help.