Child had diarrhea since sunday. was vomiting but that has subsided. he is also complaining about stomach pain. he is 3 years old?

Common problem: The average kid his age has this problem 1-3X/yr. It is usually triggered by a self resolving gut virus. Treatment is based on assuring fluid status enough that they pee every 6-8 hrs. Rehydration fluids/applesauce/fresh bananas/ rice /breads are all helpful in maintaining fluid status and slowing stools. The stomach pain/cramping improves as healing occurs. See doc if poop has blood in it.