This Is A Two Part Question. The Top Of My

This is a two part question. The top of my butt crack has been itching for a while now and its spread to my cheeks, i try not to scratch it but sometimes ican't help it. When i take showers i use HOT water on the area and it feels so good i keep, but i noticed that it's becoming discolored. So any advice on the itching and the dis-coloring?