Mystery bump on vaginal lip

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 Hi all, every now and then I get a horribly painful bump on my labia; last time, it lasted roughly 3 weeks, and although it finally healed several weeks ago, I have a prominent purple scar where the bump was. I'm in a strictly monogamous relationship, and he and I were virgins before each other, so it's highly unlikely that it's an STD - more likely an ingrown hair or a pimple. (I did pop this one and found pus, but even though it's "empty" now, it grew even bigger 😭). I find that they normally happen if I'm unshaven down there, so I went ahead just now and shaved. Afterward, I dumped into my underwear (cotton, of course) enough baby powder to change ten diapers, but I'm really concerned because of how painful and recurrent this problem is. Does anyone have any tips about avoiding ingrown hairs or pimples in the vaginal area? I shower every day and don't use any perfumed soaps (I usually use all-natural stuff), so I dont think its a hygiene problem. I'm just frustrated because the pimple/ingrown hair thing is so big and it impedes my enjoyment of sex with my partner. Please help!