There is a good. Here are the most common reasons for cats that are low in energy and also experiencing a change in eating or drinking behavior. Taurine is not created organically in the feline body so it must be derived from food.
While we have previously focused on physiological reasons why a cat may be vomiting and not eating it is possible a psychological problem may be the root cause. Your cat is vomiting and not eating. If a cat is not eating it will experience a taurine deficiency. If your cat not only stops drinking water but also throws up it is most likely due to the presence of a systemic disease.