On Monday, my 2 year old son was vomiting and had diarrhea. It was a challenge to get him to eat and drink. Tuesday morning the vomiting stopped but he still has diarrhea. He didn t really eat throughout the day, but seemed hungry for supper both those nights. The only thing he wants to drink is water. Today, he woke up this morning and had a little breakfast, some water, snack and lunch. We had two incidents today where his diarrhea was so runny, it was strictly fluid that not only formed a puddle when it came out his diaper, but whatever was left in the diaper, I poured in the toilet. I have two concerns: 1) how can we tell if he is dehydrated; 2) he is not peeing. I called his doctors office and they said he has a flu and I need to keep him hydrated. Is just drinking water okay? How much should he be peeing?