Please help for cramps when I run?

When I run for my school's sports prep workouts, I get a terribly painful side cramp to my left side. I do everything I possibly can to prep for the running which may be a monster mile, sprints, 30/30's or 15/15's. I try not to eat too much on those days, I drink water, breathe deeply, and stretch. What do I do to help? P.S. the pain is usually so bad I almost double over, but it's definitely a cramp. It comes in little jolts, it's always bad but every 10 seconds or so, it jolts and gets incredibly painful it makes me almost cry. It starts out slow and small, but as I run gets worse.