Do not worry, this is normal. Is it your first time having sex? If you have just recently started having sex, than this often occurs. It will gradually die down, but often for many people the swelling will still sometimes occur, along with redness.
Answer: It most likely means that one is having an allergic reaction to something that has come in contact with the body. To get rid of an allergic reaction, take a dosage of benedryl, and go see a doctor immediately.