Hello, Itchy, hard knots on the buttocks occur commonly due to folliculitis, hair follicles, warts, boils, skin abscess, cysts that may be caused due to allergy or poor hygiene. It may be indicative of high glucose level in the blood if you are not diabetic. If diabetic control your blood glucose at all cost. cut on refined floor, sugar or alcohol intake. Stay away from addictions if any. Maintain better hygiene. Take bath regularly. Change clothes daily and wear soft cotton clothes. Take more vegetarian food. Take plenty of water. Avoid oily junk food. You can apply hydrocortisone ointment on the area affected to ease itching. Do not touch or scratch. If its ripe and painful, get it drained and cleaned in ER, get antiseptic dressing done. You can take a course of Augmentin, orally to get rid of it. Taking a balanced home made diet will also help you get rid of it. To be on the safer side you can get STD tests done. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician