My 9 months old son has high temperature 39.4 degrees and he is vomiting and has diarrhea?

Some basics: This sounds like a common virus that infants get an average of 1-3X/yr. If they can take in ice chips or small quantities of fluids enough to pee every 6 hrs & appear alert, you may be able to manage at home. The fever is not as important as fluid balance. The high fever should decline some after day 1 & the vomiting subside some. Chilled applesauce/bananas help firm stools.If he spooks you go in