My daughter had the flu and vomited for several hours, nonstop. When she couldn't tolerate even a teaspoon of fluids, the doctor recommended she go straight to the hospital.
She was put on IV fluids immediately and perked up after very little time. She was still put on the BRAT diet (diarrhea diet) when she got home. That included Bananas, Rice, Applesauce and Toast.
What I learned: Call your doctor if you have questions...no matter what time it is.