Me And My Boyfriend Had Intercourse. When I Got Home, I Noticed My Private Was Inflamed And Burned When I Peed. We Used A Condom. What Is It?

I've been checked for STD's, and I'm clean. We used a condom, I'm thinking I'm allergic, but I've used condoms before, and nothing happened. He didn't finger me at all(so no bacteria from his hands could of gotten down there), so I'm just really confused.