Itchy butt

This is super embarrassing to ask but I need some insight until I go to the doctor. For some reason, before I have to poop, my butthole always itches. It could start itching up to 2 or 3 days before I poop. And it typically stops after I poop until the next time I have to poop. I’m a super clean person. I always wipe really good plus take showers after I poop. So it can’t be my hygiene. I’ve also been tested for Chlamydia and Gonorrhea in case that information is important. Anyone have an idea of what could be the problem?