It could be fungal infection or eczema. The treatment for both is simple. Do not apply soap on that area and do not self treat with over the counter steroid creams. Mistreatment with steroid creams and self treatment with cheaper medicine is the most common reason for recurrent disease. Kindly send photos for accurate diagnosis or visit a dermatologist. If this is fungal infection, it needs to be treated as early as possible as it will spread further on your body  and also to other people in the household.