I have a small bump on my inner vaginal lip and it stings sometimes. i know it's not an sti because i recently had a pap test and it only comes when i'm about to get my period. what could it be?

Wrong test: Hi. A Pap tests for cervical cancer, not STI's. So please do not conclude it's not an STI from a normal Pap smear. Talk with your gyn about this; she/he will know what to consider.

Labial irriation: This bump could be a gland that serves to lubricate the labia and vagina, which is changes with hormone secretion. Alternatively it could be a herpes lesion that comes out around the time of your menses. A pap test will not necessarily dx herpes. Ask your medical provider to culture it when it presents just to make sure. There is medication available to suppress herpes infections.