Loose motions with an upset stomach are often due to infection or food irritation and usually improve with simple care. Drink plenty of fluids, such as water and oral rehydration solution, to prevent dehydration, and eat light foods like rice or toast while avoiding spicy or oily meals. Rest well and maintain hygiene. If needed, a doctor may prescribe medicines based on your symptoms. If it continues for more than a couple of days or you feel weak, consult your doctor.