This is caused due to dehydration, use of drugs and due to allergic reaction. Usually vulva swells 3-4 times bigger than normal. It gives different feelings like gagging or choking.
What Causes Uvula Swelling?
I am not a doctor , so I suggest you go and see a doctor. That said here is a page that shows what can cause a swollen uvula. Www.netwellness.org/question.cfm/46955.htm