I am 15 years and female. I have a chronic back injury to the sacroiliac joint and I play field hockey 3 times a week. Majority of the time (ALWAYS before I exercise) when I eat a meal about 10-15 minutes later I need to poo and it's a cramp sort of pain in my stomach as well as a nearly nauseas sickness. The poo is runny like diarrhea. Sorry for the vividness, I am very tired of it now! Can anyone relate or know anything?