Got a sick cat? Perhaps its malingering instead. That's right: cats can act sick when they're perfectly healthy simply because they didn't like what you've done (i.e. change their routines):
When the cats experienced what were called "unusual external events," such as a change in feeding schedule or caretaker, the healthy cats were just as likely to exhibit sickness behaviors as were the chronically ill cats. The two groups had the same number of sickness behaviors in response to unusual events, and both groups were at more than three times the risk of acting sick when their routines were disrupted.
Remember that cat on a trampoline? Its owners are so going to pay for that by cleaning up tons of hairballs!