Talk to Dermatologist on Pustules

only one large pastule on buttock caused acute pain and redness emitting heat was self treated with many ointments specifically travocort and medicine cip-rx ended up leaving scar after emitting pus and blood from that pimple or breakout. Now still same condition continues even after maintaining complete hygiene. 2, 3 appeared then treated same as previously now it appeared again l want to ask from a dermatologist or skin specialist for the cure as I am in pain and trouble while sitting and lying down. Why it repeatedly occur and type of allergy is it???