Puffy/swollen lips

My S/o and i had sex the other day and not only did we sit in cum for a moment (i was on top and was taking a moment to catch my breath), he admitted i wasn't wet before he put himself in. Immediately after, i felt burning down there. It doesn't hurt when i pee, it just feels uncomfortable. I finally looked in a mirror and my lips and puffy and sensitive, kinda sore even. It's not as bad as it started out and we had sex earlier and it was fine, i'm just.. what's wrong with it? ..that's such a vague question but if anyone else went through this, it'd make me feel better 😅