You may be suffering from tinea cruris which is fungal infection of the inner thighs and genital area. It can be treated by taking four to six weeks of anti fungal treatment which includes tablets along with creams. Do not use soap over that area. Mistreatment with over the counter Steroid containing creams lead to repeated case of recurrence and also side effects due to application. Do not use steroid containing combination creams. Please consult me in private chat with photos for detailed prescription. Do not delay treatment as it may spread further on your body and also to other people living in the household. Donot use deroben as it is very strong cream and is not used for fungal infections. In fact due to its side effects it is not used for treatment at all by any Dermatologists