I am a beginner runner and at this point can run four miles at an 8:30 mile pace. (I know, not so good, but I'm only just starting!) Occasionally*, I get a pain in my stomach, or just under my stomach, that feels like I am both starving and nauseous at the same time, after running only 10 minutes. I'm not overweight and I play tennis as well, and don't experience these problems during something as long as an hour and a half set. I don't know if it is an acidity problem or something like that. Does anyone know what my problem might be, or does anyone have the same problem?
Possibly a stitch (cramping). Could be due to not drinking enough water, so the muscles are becoming dehydrated. make sure you warm up adequately too and start slowly, building up speed gradually.