My 6 years old daughter has stomachache from yesterday. She vomited once today morning, passed stools once. It's not watery lose motions but a little soft stool than usual. She's not eating anything. Forcefully giving her few sips of water. She has not been eating well from almost 10 days. Till yesterday she had no other symptoms or complaints. Passes stools once everyday. What could the reason for this? She doesn't have a fever or any other symptoms. Loss of appetite and no interest in food is my major concern. She's lost weight and looks weak and tired. Does it require any tests or diagnosis to investigate the cause?