Why are My Labia Swollen?

Dear Betty,
Thanks so much for taking the time to answer.
I'm 19 years old and sexually active, i have a bit of a problem with the fact that my labia majora is so swollen after oral sex or just stimulation. My partners have either given oral or tried to stimulate it but i don't really feel anything and at the end of the night its so swollen that i had to try to cool it down with ice water but it usually takes 2-3 days to go back to its normal size.
Could this be some kind of infection? Or is it just me?
Dear R,