Well, the most common cause of diarrhea is a virus that infects the gut. The infection usually lasts for two days and is sometimes called stomach flu. Diarrhea may also be caused by: Infection by bacteria, Infections by other organisms, Eating foods that upset the digestive system, Allergies to certain foods, Medications, Radiation therapy, Diseases of the intestines, Malabsorption, Hyperthyroidism, Some cancers, Laxative abuse, Alcohol abuse, Digestive tract surgery, Diabetes, Competitive running. Diarrhea may also follow constipation, especially for people who have irritable bowel syndrome. Studies have found as few as one in 100 people undergoing gallbladder surgery or as many as one in three develop diarrhea. The diarrhea may last for years. Treatments you and your doctor may consider for controlling your diarrhea include: Anti-diarrheal medications, Medications that impair absorption of bile acids. I hope this will help you.