vaginal bumps/pimples. how to get rid of them?

I've been frequently getting lumps/ pimples without the pus in my vagina. they started three years ago, they come and go throughout my cycle. went to the clinic but the nurses ddnt say anything about an STI or something like that mom says it could be because of the type of the tight underwear/jeans. I just want to get rid of it cause I don't want to feel all awkward when my boyfriend goes down. please help, what to?