Getting a (side) stitch - Abdominal Pain
A "stitch", also known as a "side-stitch", is a sharp pain just below the rib cage, usually felt whilst exercising, e.g. running.

It is caused by a cramp in the diaphragm muscle which comes about when the ligaments connecting the diaphragm to the liver are stretched. The risk of developing a "stitch" can be reduced if you take the normal steps to reduce the risk of experiencing any type of muscle cramp. This entails ensuring your body is properly hydrated and that the diaphragm muscle is properly "stretched" before exercise. You are more likely to develop a "stitch" if you exercise too soon after eating, since the liver becomes heavier when food is being digested and the aforementioned ligaments are already stretched.

As it is a cramp, a "stitch" can be treated by temporarily reducing the intensity of exercise, (thereby reducing the work conducted by the lungs and diaphragm), and also by massaging the abdomen where the "stitch" is felt.