Gastroenteritis, or the stomach flu, is often caused by viral or bacterial infections that lead to inflammation of the stomach and intestines. This inflammation can cause the pancreas to become inflamed as well. The pancreas produces digestive enzymes and bile, which help break down fats. If the pancreas is inflamed, it may not produce enough bile, which can lead to white or pale-colored stool. In most cases, white stool after a stomach bug will go away. However, if it persists for more than a week, it is important to see a doctor.