PLEASE don't feed them fresh fruit. That is very bad for them. Chinchillas do best on a bland, dry diet. They need loose hay and alfalfa based pellets. The pellets should not be a mixture of things but plain pellets such as Oxbow or Mazuri. There are others I can recommend if you don't have access to those. Fruit and other treats should not be mixed in at all. Your chin probably feels sick after eating those things and may explain it. The texture alone can serious intestinal complications with chins.They come from a desert climate and wet things are not part of their normal diet.