it just burned so bad to pee after sex :(

So I just had sex with my SO, and we hadn't had sex in 3 weeks. Right now when I used the restroom to pee, it STUNG so bad!!! Recently I've been kinda itchy down there and I'm thinking it's either because I might have an allergic reaction to summers eve which it's been a week since I used it, or I have a uti! I'm not sure! But it burned SO bad once I peed right now! I'm also on the IUD so idk if that could be a factor too :/ 😩😩😩😩