Pimple (folliculitis) Cant be std also.

Hi, some 2 months back i got a pimple in my vulva region on left side which was hard in the start then i consulted doctor she said it is folliculitius in vulva region so she gave me T bact cream some medicine it took around a week then pimple was kind of cooked then it got head and i popped pimple removed its puss and little blood and the pain and all went away but yestrday i saw again i got similar pimple on my panty lining in right side. Earlier also this happened when my period was about to come now also it is happening like when i am expecting periods. I also used some tight outfits ystrday and in one night i got this cyst like bump. I dont understand why it is coming again and again i feel much scared than earlier. Please let me know what should I do. Does this happens due to swimming chlorine water or due to hair was irritated :( I am not sexually active so it cant be STD also...