Always check in with your pediatrician if this is your child's first bout of stomach flu, or if her vomiting or diarrhea is particularly severe  The doctor may want to assess your child's hydration and rule out other conditions  (Vomiting and  diarrhea can also be among the first signs of meningitis, a bowel obstruction, or poisoning, to name just a few) And your physician almost definitely will want to see your child if she's a newborn  Also call if any of the following symptoms pop up

☺Blood in the stool or vomit
 ( look for   a black or maroon color, not bright red)
☺High fever ( above 102.5F)
☺Extreme lethargy or unresponsiveness
☺Unusual irritability or fussiness
☺Sever or increasing pain
☺Vomiting that does not subside after three days, or in an infant, vomit that is green
☺Diarrhea that doesn't begin to go away after seven days

 Magazine "Parents"