Cat has poop sticking to ....?

She doesn't have any fur around her bottom but she does have some poop that is stuck on it. I tried to clean it with a washcloth but she scoots away. I'm afraid to rub too hard because I don't want to hurt her. She doesn't meow or anything when I try to wipe it. She has been behaving normally, not scooting her bum or anything. She cleans around her bum but doesn't actually clean her bum. This just started recently and we DID change her litter. We are changing the litter back but what can I do in the meantime to get the dried poo off of her bum?