Stomach hurts so badly?

Why? The pain is like right around the on of my pants (if I had any, but I'm wearing sweats today) it feels like somebody put a 2 ton bowling ball on it while I was sleeping and also kinda feels like somebody is stabbing me with a dagger that's just been sharpened. Why? I'm 13 and a girl? I've also been really uber hungry lately and uber moody