What does it mean when the inside of your vagina is swollen an hurts when you try to have sex?

Vaginitis : You probably have a condition called vaginitis , which is an inflammation of the vagina associated wih swelling and pain.This can be due to infections like yeast, bacterial and viral or it can also be a reaction to the latex in the condom or lubricant. Some women have this reaction to some contraceptives. See your provider for a discussion.

Infection vs allergy: Infection is a possibility although based on your description, it is hard to really tell which one it may be. I encourage you to provide more details. Swelling may be a symptom of allergy especially if you use condoms and you are allergic to it. Vagina may become moist and somewhat swollen during petting but it should not be to the point to make sex uncomfortable in most cases.