What causes for a kitten to become sick?

If you let your kitten outside to play, it might eat quite a deal of grass. It can also start being sick as a cause of having alot of hairballs. If your cat has a hairball, it will start balking wich looks like it is away to be sick but it won't be so don't worry. Another reason is food. Either the kitten ate too much in one go, or the food doesn't agree with it.