Irritable bowel syndrome, diverticulitis, and viral and bacterial gastroenteritis cause stomach pain accompanied by diarrhea, according to Healthline. Excessive amounts of alcohol, dietary changes and indigestion may also cause stomach pain and diarrhea.
Irritable bowel syndrome, also called spastic colon or mucous colitis, is a collection of symptoms including cramping, stomach pain, diarrhea and bloating, according to Healthline. Previous bacterial infections increase the risk of contracting irritable bowel syndrome, though the exact cause of new cases is unknown, as of 2015. Diverticulitis is the inflammation or infection of diverticula, which are small pouches that form most often in the lower part of the large intestine in those over the age of 40, according to Mayo Clinic. In addition to severe stomach pain and diarrhea, people suffering from diverticulitis may exhibit fever and nausea.
Viral gastroenteritis, or stomach flu, is an intestinal infection typically contracted through contact with an infected person or the ingestion of contaminated food or water, according to Mayo Clinic. There is no treatment for viral gastroenteritis, and while most healthy people recover without complications, the condition can be deadly for people with compromised immune systems, infants and the elderly. Bacterial gastroenteritis, or food poisoning, is caused by eating food that contains toxins or infectious agents, such as viruses or bacteria, according to MedicineNet.