I keep getting a recurrent cyst in my labia that wont pop and its very painful when its there. It comes and goes every few months. Whats causing it?

Blocked Bartholin. The bartholin gland in the labia has a duct that opens just inside of the labia. When that duct gets blocked, the gland will swell or get infected. Washing carefully and keeping the vulva free of oils and irritating soaps will help prevent the recurrances. Sometimes the cyst has to be permanently opened in a minor surgical procedure called marsupialization of the bartholin gland.