Suggest Treatment For Dehydration And Stomach Cramps Caused After Stomach Infection

My six year old granddaughter has had stomach virus and this is third day. dehydration is a concern since she only wants a few sips of water. sleeping a lot, stomach cramps continue, leg cramps. throwing up is not as bad but still had one bad spell this morning. Not sure if you go to dr, urgent care or emergency room for something like this