There are many causes involved with abdominal pain, and in many cases, it's just a symptom! You can never be sure and zero in on a particular cause till you consult a physician and get your condition checked. Some of the many causes of abdominal pain are constipation, indigestion, food poisoning, stomach flu, food allergies, menstrual cramps, urinary tract infection, Crohn's disease, endometriosis, kidney stones, gallstones, hernia, pelvic inflammatory disease, ulcers (stomach), lactose intolerance and gastric trouble. Your question is quite hard to answer as we cannot zero in on a particular cause without examining the other symptoms. The most common for women is menstrual cramps and the most common cause for men is indigestion.