Picky eater?

I have had my chinchilla for over a year and I'm having troubles understanding what's going on with her now. I have never had this problem but just about a week ago she stopped eating her pellets. I have given her the chinchilla food that is blended with all sorts of things but contains mostly pellets. She would eat every last bit. This last bag of food I got her was not the same one that I usually got because they were out of the usual stuff. I never noticed until about two days of her having it that it had way too many treats in it. I started to notice that it was making her poop smaller so I switched to straight pellets. She wouldn't even touch her food after that. Then she stopped pooping on a whole for about three days. She was still drinking and eating hay and eventually she started pooping a little more. I brought her to the vet and he said there are no signs of her being constipated. He checked her teeth and found that one was kind of sharp so he trimmed it down and found that she has lost a lot of weight. He thinks that she's only being picky now. He also gave me the critical care powder to give her if she didn't eat that day. She still has not touched the pellets and trying to do this critical care is really tough considering how fragile they are. Will she eventually eat the pellets or will they be so stubborn and starve themselves to death?

(I am offering no treats. Just food and hay.)