When i run i get sharp stabbing pain in right side?

Muscle spasm: When you run, you use the 3 layers of muscles in your abdomen. These flat muscles, when used, can "spasm" or contract very vigorously. This causes a sharp stabbing burning pain, a lot like a charley horse in the calf (also a muscle spasm). If this happens to you, stop running, rub firmly right on the stabbing painful area, and the muscle will relax; just like when you rub your calf. Good luck!