Itchy

So I've never had this problem before, my butt is so itchy!! It's been this way for like 7 months. I wipe good, I shower everyday if not twice a day, I change my underwear quite often maybe 3 times a day. My butt hole is so freaking itchy. It's hard to explain but only one side/inside itches so bad!!! It gets to the point that I can't tolerate it and have to scratch it...or I scratch it to much or rough and gets bloody or super sore. Please tell me why this is happening!!!!