What Is Hole In Butt Cheek Oozing Brown Or Red Mucus?

I have a hole right between my butt cheeks that leaks mucus that is sometimes colored with a faint brown or faint red. It is not my anus that is leaking. It does not hurt to sit, however when I do sit-ups and roll on it, it does hurt like a bruise would. It stains my underwear and causes that area to harden. It does wash out, (not the red stains.) I stuck my pinky in there and it does not go very deep. Maybe 1-2 centimeters. Also it smells really bad sometimes, and other times it doesn't.