| If he has been vomiting all day while you were at work, and is continuing, yes, you need to take him to an emergency vet. Vomiting for long periods will dehydrate them very quickly, and isn't any fun either. The act of vomiting when they are straining all their muscles, further dehydrates them and wears them out.
If he has stopped vomiting, you can wait for about 6-8 hours and then if he hasn't vomited by then, you could offer a small amount of water and see if he keeps that down. If so, keep giving small amounts of water every hour for a few hours, then graduate to a very bland food like Gerber or Beechnut plain chicken baby food, or plain white meat chicken (canned is fine) and white rice (minute rice is fine) and give small amounts of that. The ratio should be 1/4 to 1/3 chicken to 3/4 to 2/3 rice. But if he can't keep any of that down, he needs to go to a vet immediately. | 
