Hello, The most common cause is fungal infection due to warmth & sweat in the area affected. Maintain hygiene. Apply clotrimazole on the affected region. Take antihistamine at bedtime to get rid of pain and itching. Take a course of oral antifungal medication. Cysts, boils, warts, or skin abscess also occur under the buttocks. Allergy to hygienic products, chemicals, or plants can also cause itchy, red bumps on the butt. Avoid the use of harsh chemical products. Take care of your hygiene, keep the area under the buttocks, clean and dry. Apply a water-based moisturizer. Genital and perianal eczema is a common skin condition marked by itchy and inflamed patches of skin around the opening of the anus and the skin between the cheeks of the buttocks. To treat it apply cold compresses. It will help relieve the itch. Apply ointment containing topical steroids to control the spread. Wear comfortable, loose-fitting clothing so that the wound is not hurt by the irritation and friction. It is best to avoid wearing tight trousers. Avoid wearing Nickle ornament anywhere in your body, it may trigger the symptoms. You can get an STD test done to be on the safer side. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K, General & Family Physician