P.K.
Sometimes the very top of the butt crack can get dry and literally crack...usually hairline cracks. Try either a diaper cream or I've used petrolium jelly on my daughter. It soothes it, and protects it from "the elements", and heals in fast order. Another thing to think about... my daughter also has a terrible time with wiping after going potty, and after a few times of this, develops a terrible "rash" (or rawness) on her front area, which can lead to the back, as well. Petrolium jelly can soothe this as well, but I've even had to get some vaginal cream at times to take the sting and itch away. So that's something to think about, as well. Hope this is helpful! Good luck!