Single small, hard, white bump on vagina lip.

A few days ago I noticed down there was a little irritated on one side, but I was on my period so I didn't think much of it. But now I notice a small, hard, white bump on the lip of my vagina. It's about the size of the eraser tip of a pencil. I don't know what 'cauliflower shaped' looks like, but what I have is round, and smooth. It looks like kind of like an enlarged whitehead, like the white could be puss or something like that. It's hard to properly see it, you know. It's a little tender when pressured and mildly itches occasionally. I barely notice it's there sometimes. There is no strange odor coming from my vagina, but I've noticed yellow-ish discharge. I do shave regularly down there. But a week ago I had a fumble with unprotected sex. I didn't notice anything wrong with him. If anyone has any ideas what it could be please, please, please let me know. I'm stressin about this so much.