Pasty butt is another indication that temps are too high. It might sound dramatic but when I first started out with temps that high I noticed a smell like chicken cooking! I knew then that high heat is a killer. It's only needed in the first few days to get them going then you want to lower...
Are they laying flat, panting or hanging out at the border/walls of the brooder. I think your heat is too high. They need a way to get out of the heat. A cool and warm zone..... I DO offer a small bowl of chick grit at this age and therefore I don't worry about them eating pine shavings.
Are you giving Chick grit? Trying adding water to chick starter. When you say you are cleaning pasty butt, is this re-occurring?
Above questions are very important for troubleshooting:
What are you using for brooder and heat source?
Feeding what?
How's the temp in the brooder?
What are the...