The same thing has happened to me! It hurts when I sit down, sometimes it itches, and the lips are really swollen and red along with my hole. idk what it is?!?!?!
Sometimes I get like this from irritation or I get a cut inside just from dryiness and or roughness of sex. It should go away soon otherwise talk to your doctor. Could also be a cyst. I am not a doctor though so good luck