I just got a new kitten that is so sweet. But lately she starts to bite me when I rub her stomach. Why does she do this?
Cats bite for very specific reasons. They bite when cleaning themselves, when eating, when playing, when attacking and when they are defending or protecting themselves. There is sometimes a fine line between playful and defensive bites, and defensive and attack bites, especially in kittens.
Your kitten is most likely becoming overstimulated. Young cats, and sometimes even older ones, can lose sight of normal behavior boundaries when they get worked into a playful frenzy.
Many cats are also sensitive in the stomach region. You could literally be rubbing your cat the wrong way, so be sure to take care when petting this area. It also puts your kitten in a more vulnerable position, so she might be more inclined to attack. And remember that your kitten can't verbally tell you to stop. A sharp bite can be an effective way for her to communicate, "Quit now!"
Your kitten probably does not have a stomach health issue, but it also couldn't hurt to have your veterinarian check out your pet, just to be safe.