I had one about
6 months ago. It started out the size of a pea right outside my vaginal
opening and didn't hurt at all. It stayed that way for months, then it started getting bigger. It ended up about
half the size of a golfball and I couldn't take the pain anymore. I went into the ER and I had it drained. Worst experience of my life, I was litterally traumatized from it (I blame it on the ER doc though, not the actual procedure). I honestly don't think it had anything to do with my Crohn's.
Maybe you keep getting them because they drain and keep filling up, I'm just guessing. When I had mine drained she stuffed it with gauze which I was to keep in for 2 days and gave me an antibiotic to prevent it from coming right back.