I Can Feel Like A Rash Inside Of My Butt

I can feel like a rash inside of my butt crack it's only at the top. It doesn't itch or burn only hurts. It has been going on a couple days now. It hurts when I sit up, walk or sometimes even lay down. My mom had tried to look at it because she is a nurse but I couldn't take the pain when she tried to pull my cheeks apart. I've put diaper rash cream on it and baby powder it helps for a little bit then when I get up hurts all over again. What could be wrong?