Hello, Thank you for asking at HCM. If you are having stomach ache with diarrhea the most likely cause is a viral infection. It is generally taken orally by contact with food that was not so fresh or can be transmitter from someone else that has similar symptoms. I would recommend you to relax and know that it is not dangerous and generally it goes away in a few days. I understand that pain can be bad sometimes though.Even the bright yellow color of the stools is normal with diarrhea, it would be more serious if you had blood with the diarrhea. So to close it: 1. make sure you keep yourself hydrated: drink frequent small amount of fluids 2. ORS are the best substitutes of fluids and electrolytes, take them regularly 3. do not touch the food of others as long as you have diarrhea so you do not infect them 4. take paracetamol orally to help with pain and local warm compresses to help with abdominal pain. If it is really stomach pain Omeprazole might help a lot. 5. Do not take medication for diarrhea unless you are travelling. They have the risk of prolonging the infection and causing side effects 6. wash hands with warm water and soap regularly 7. if no improvement in 3-4 days or earlier if any worse you will need to see your doctor. Hope this is helpful and answers to your question Best regards, Dr Antoneta