Pain under rib cage is commonly referred to as a side stitch. The occurrence of side stitch is most common during exercise. It is also known as 'Exercise Related Transient Abdominal Pain' (EATP). Such pain is one of the common forms of abdominal pain. It can be the result of problems like gallstones, appendicitis, fractured rib cage, etc. These and many such causes of are described in this article.