To target this often overlooked muscle, raise your right arm straight up and bend your trunk toward the left. Hold for 30 seconds, release, then stretch the other side. Sometimes it's as simple as decreasing your intensity until the pain subsides. Try lowering your arms and slowing your pace the next time the pain hits. This helps to stretch the diaphragm.
Some people also find exhaling forcefully when the opposite foot strikes the floor to be helpful.
For instance, if the pain is in your left side, exhale forcefully every time you land on your right foot. Drink more fluids before exercise. Dehydration can cause muscle cramps. Rub it away. Massage or press on the area where you feel pain.