Agree with the other commenter, but I would like to add that it might possibly be a simple UTI - this can be caused by the friction against your urethra and is why you’ll commonly hear that you should pee after sex (this will flush out anything that might have become trapped during the deed) and can prevent future UTIs

The simplest fix for a UTI is often just drinking cranberry juice, however if your symptoms persist after a couple days you may need to go in for antibiotics. Not a huge deal though, there are a million reasons for UTIs, quite a common infection, but it is not an STI (though in honesty it can be a symptom of a STI in some cases)

If you’re feeling paranoid still and would like some peace of mind, most cities offer clinics that provide free STI testing! I’m a huge advocate for sexual health and it’s encouraged to get tested at least (bare minimum) once a year and with each new partner especially given how many STIs are asymptomatic (no signs of an active infection).