Many causes. Lots of things can cause the stomach to hurt down low. The organs in the lower abdomen include the large intestines, bladder, and ovaries/uterus. Hernias can also cause pain in this area. See your doctor, and be prepared to answer the questions: is it associated with eating? What makes it worse/better? Do you have any diarrhea, constipation, nausea? Is it associated with your period? With sex?