I have a cluster of itchy blister on buttocks and never had it before. they look they are water filled blisters. can u tell me what it could be?

Maybe herpes: Sounds like onset of herpes simplex infection. You'll know in a day or so--lesions will probably hurt more and itch less. If they stay itchy, possible fungal infection. For herpes, BHT (available on line or health food store) 2,000 mg per day (taken in divided doses). Lesions should clear up in a day or two. Another "home remedy" is to apply DMSO ("horse liniment") from a veterinary supply.