How old is Evie? Is she still a young chinchilla? Chinchillas don't drink as much water as a rabbit or a guinea pig so if you have had experience with those in the past it will be different with a chinchilla. They should be drinking daily though. As Sandi said you need to keep a close eye on her--is she eating, drinking and pooping? If she isn't doing one or any of those things that is a very bad sign in a chinchilla. Going back to the treats you give her again how old is she? A chinchilla under 6 months should get no treats at all. When they are old enough the treats chins should get are 1/2 of a bite size plain shredded wheat, a pinch (small amount) of old fashioned cooking oats, a plain cheerio, dried whole or crushed rosehips. A small amount of plain uncooked pasta is ok occassionally.
If you notice Evie not pooping please get her to the vet ASAP. Mark her water bottle with a marker to check the level of water to see that it is going down, if it isn't get her to the vet ASAP.