Finally, strengthening the abdominal muscles, lower back and other muscles of the core (obliques, hip flexors, glutes and hips) with a good strength workout can help stabilize this region while you're running. While you can't completely stop the bouncing nature of running, you can make your body stronger and more resilient to the effects of that jostling.
Luckily, side stitches seem to affect beginner runners more often than experienced runners. If you're new to the sport, you're probably experiencing a temporary nuisance that will drop off over time.
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