Why do I get a sore tummy while running? Really painful makes me want to faint makes me feel sick.

Breathe correctly. When running, make sure you are breathing correctly- inhaling should make your chest expand, exhaling, should deflate your chest. Some people do the opposite with resultant pain.
Fatigue. Sounds like fatigue of the abdominal muscles but you need an exam to rule out any other abdominal problems. Go see your pcp.