The same thing happened to me today. Did it go away?
Just one lip is swollen and the skin covering the Clit.
My only guess as to what happened is that he either was literally applying suction to the labia and for such a long period or so repeatedly that there was a build up of fluid edema; or he bit it, bumped it with his chin or hand or caused some abrasion injury; resulting in inflammation. For it to happen so suddenly and only after oral sex I can't imagine it being anything other than minor swelling, it should go away in a few hours.