My cat is vomiting and has severe liquid diarrhea. Is it urgent?

It definitely sounds like BoBo has an upset tummy. I am concerned about the amount of vomiting and diarrhea that you have described. Possible causes for this to happen acutely include bacterial or viral gastroenteritis, pancreatitis, toxic exposure, intestinal obstruction, dietary intolerance or food allergy (this would happen if he ate human food he shouldn't have or if you recently changed food or treats), irritable bowel syndrome, intestinal lymphoma, or other internal medicine issues. I think that BoBo should see a vet as soon as possible to start with bloodwork and maybe x-rays depending on the findings of the physical exam. Before you go, check around the house for anything that BoBo may have chewed on, like hair ties, string, carpet, or chemicals.

You are right in not feeding BoBo anything, but encourage him to drink water, chicken broth, or pedialyte to try to maintain hydration. Cats can also get electrolyte imbalances soon after having voluminous vomiting or diarrhea. Depending on test results, your vet may prescribe medications for nausea, diarrhea, or even antibiotics and gastroprotectants. If the bloodwork shows severe abnormalities or the symptoms persist despite medications, BoBo may need IV fluids to rehydrate him and correct electrolyte abnormalities.

If you have additional questions I can answer, feel free to choose a consult so we can answer them.