Pedialylte or Gatorade. But With Gatorade you might want to dilute one part water one part Gatorade at least until your stomach becomes more stable. There is nothing wrong with good old fashioned water in moderation. We should all drink at least a half gallon of water per day, more if you are dehydrated, vomiting or have diarrhea. Good old fashioned real chicken soup is good for you if you can tolerate it. Especially if it was homemade. The rendered chicken fat has natural antimicrobial characteristics. Good luck.
You could get some of that, oh, I don't remember what it's called. It's in the baby isle at supermarkets, to replace electrolytes in babies who have been sick. It's a liquid, looked like small versions of bottled water.