I have a gone to a colo-rectal surgeon to have what I thought was a pilonidal cyst but he said it was not and that it looked like a blister that popped. Now though 8 weeks later the one spot has turned into a line but like a welt. it also feels like some sort of blister but it's a different texture than the rest of my healthy skin. It's growing down my left buttock and it seems to be sloughing off skin along that line.