There is also a possibility you are running faster than you are conditioned for. Usually, especially if you are just starting out, cramps, shin splints, stomach issues, all happen when you try too much too soon.
If you get a cramp, stop, raise your arm on the side your cramp or stitch is on (raise it straight up over your head) and take some deep breaths, this will usually alleviate the issue temporarily. Try slowing down a bit (trust me, I've been there, lol)
PS, I've raced a few marathons as well as all the shorter distances, and found a great resource for a lot of my running related questions here:
www.runnersworld.com/forums
lol, PSSS: The Garmin Forerunner 205 is a great training tool