Hello and welcome to HCM. Thank you for your query. The possible conditions that could be causing such a presentation are the following: -Cyst -Bartholin s cyst -Irritation from friction, soap, clothes, etc. -Sexually transmitted diseases I would like to ask, how exactly the STI was dismissed? Was it just with a physical examination, or were you screened as well? I personally advise a screening along with a physical examination, as some individuals and some infections do not always present in textbook-like pattern, and for such cases, screening is very important. As you recently had thrush, I would like to ask if you were appropriately treated? Which medications were advised? Did you complete the course advised? Are you currently experiencing any such symptoms, similar to what you experienced when you had thrush? Keeping your history of frequent cysts in mind, it would not be surprising for you to get cysts, or folliculitis, or abscess s elsewhere; but a cyst inside the vagina will have to be looked into with more diligence. I hope I have succeeded in providing the information you were looking for. Please feel free to write back to me for any further clarifications at: http://doctor.healthcaremagic.com/doctors/dr-shoaib-khan/64581 . I would gladly help you. Best wishes.