Repeated cysts in vagina?

I keep getting cysts in my vaginal walls. Like a hard small ball inside the “flappy parts” that will usually pop. But isn’t a pimple. It’ll just be about one once a month. I just don’t know why. I take a bath usually every night. I use to think it was from sex but i found another tonight yet I haven’t had sex for weeks. Is it diet related at all? is there anything I can do to prevent them? I didn’t start getting them until I started having sex but this is about my fifth within months. Last time it completely threw off my ph giving me a smell so I invested in a gel 😕