One of my chinchillas all of a sudden has had a massive increase in appetite. He acts like he is starving and when I fill the food bowl he eats constantly until it is empty. He drinks fine, looks and acts healthy, and though I've never formally weighed him he's about the same he's always been. He's about 8 years old. As far as hay goes he will not eat Timothy (unless it is kaytee branded with marigolds, then he looves the flowers), alfalfa (food is alfalfa based), or orchard grass. I just bought botanical hay to try it out, and it looks like my only other choice would be oat hay. The brand for all have been Oxbow (except the kaytee but I only tried it once.) I rarely feed him treats, and when he does get one it's a single piece of oatmeal. I'm really just wondering if I should be worried, as I don't know what causes excessive hunger in animals. Thanks in advance for any and all advice!