Pimple on Vag lip?

I know this is super weird but I get like a huge bump on my vag lip (it’s only happened like 3 times in the past 7 years) I first got it in the 6th grade and I wasn’t sexually active so I knew it couldn’t be an std and then I got it again when I first started shaving my cooter in high school and then I got it recently out of no where. idk why it comes up but the bump is huge and it’s always super tender like a cystic pimple and the only way it goes away is if I pop it and when I pop it there’s white pus that comes out like it’s a giant pimple should I be concerned? Has this happened to anyone else and what is it? Should I contact my doctor about it?