Constant stomach pain and nausea can be caused by many reasons. The most common are the following: 1, chronic cholecystitis manifested as right upper abdominal pain. If the patient eats greasy food, the pain will be aggravated, and often accompanied by nausea. 2, chronic appendicitis manifested as pain in the lower right abdomen, when the pain is accompanied by nausea when the pain is acute attack. 3, digestive diseases mainly refers to the chronic gastritis, gastroduodenal ulcer, if you eat greasy food or eat spicy and stimulating food will appear under the rapier pain, often accompanied by nausea. 4, gastrointestinal functional disease refers to the absence of obvious organic lesions, due to gastrointestinal motility weakness, the gastric and intestinal function, the gastric and intestinal function of the gastric and intestinal diseases. The first is that there is no obvious organic lesion, due to the weakening of gastrointestinal peristalsis, which can be manifested as pain around the umbilicus, often accompanied by nausea and abdominal distension. 5. Pancreatic diseases can also lead to pain and nausea in the stomach, such as pancreatitis, pancreatic cancer, etc..