vagina lump..

[beekini.livejournal.com]

I woke up 2 days ago with a really sore, hard lump on my vagina. It's on the underside of my outer lip, just across from my clitoris. Does anyone have any idea what it could be? I had an STI test a few months back and was all clear, so it's not that. Its really, really sore and quite itchy/stingy if it rubs against my pants, but you can't really see anything except redness and the whole area has swelled up. Its like a hard pea under the surface. Any thoughts? It's so sore :(