Below are two images of the large intestine. There are 3 sections visible ... the ascending colon on your right side (left in pictures), the transverse colon that goes across the top, and the descending colon on your left side (right in pictures).
Pay attention to the transverse colon in these images. I wanted to show that it can be located differently in different people. In the left diagram, it dips low; in the right diagram it sits high. So, for example, if there is pain or discomfort in the chest, it could involve the heart (angina), the stomach (heartburn), the lungs (pleurisy), or, as you can see here, an irritation in the transverse colon, among others.
That's just local pain. There's a field of study that addresses a phenomenon known as referred pain - pain that's felt away from the site of an injury. An example often given for referred pain is the burning or acute ache felt down the left shoulder and arm during a heart attack. One helpful aspect of referred pain is that it's consistent from one person to another.
If you have a pain in the area of your stomach, it may involve the stomach, or it may not. In the diagram of referred pain sites to the right, a pain in the center of the upper back may indicate a problem with the stomach. A pain on the right side of the neck may indicate a problem - not with the neck - but with the liver or gallbladder.
I think Brad Wright does a great job explaining referred pain on his blog, Anatomy Notes.