13 year old boy, pain under left lower rib cage, in shape, starts after 5-10 strides of running, thinking a stich but don t recall a specific event when this started. In good shape, ran for 20 min, on a treadmill a few days ago, everything was fine, next day tried to run again and couldn t even jog due to pain, since then it has been 3 days and sharp pain starts when I try to jog or run. I can do everything else without pain , even jump with both legs , squat, sit ups.