Hi,
Anytime vomiting goes on for more than 24 hours with a cat you should take them to your veterinarian. There are many causes of vomiting. Hairballs are the most common, but I really don't think this is your cat's problem. Other possibilities include bacterial/viral infection, organ (kidneys,liver, etc) disease, ingesting a toxin, and intestinal obstruction. I would recommend taking the kitty in to your vet as soon as possible. Here is a link to a page about vomiting in cats:
http://www.cathealth.com/vomit.htm
If you have further questions let me know. If this answers your question please click accept. Thank you.
Lynn
Veterinary Assistant
worked at a vet clinic for 15 yrs, BA in biology, have had cats most of my life