I m a teenage female, i didn t sex with any1. But I often masterbate. I have found a large pimple like blister near my anus under the vagina. This thing comes for some days n then goes away.But now it s there for 5 days n changing it s position.But before it didnt change its position.It greatly worries me what could this blister be? It seems to have pus/fluids underneath the skin but when i pearced it there was no fluids to release. It could be described as glossy and is red What can i do to treat it? Please help.