I would see your Dr. Just to make sure it's not a blood clot.
I had this, but it was after delivery. I don't know I it would be the same thing with you. The first time it happened was with my first baby, I had very swollen labia and just Iced it and it eventually went away.
I had it again this time, with my third but I ended up having a large hematoma and the entire area turned blackish purple, it started with only one labia.
I would try to stay off your feet and get an ice pack for the area. If it gets worse or painful then I would call the doctor and see what they recommend. It is probably just a little swollen due to the increased weight of the uterus, but it's always a good idea to get things checked out if you are worried. Good luck!