On weekdays I don't have time to eat breakfast, so I just decide to skip lunch, then I eat one bigger meal and a couple snacks later in the day. After first eating in the day my stomach hurts. I know its not from over eating, because I count my calories. My stomach doesn't hurt every time I eat, like for example on days I eat my meals normally my stomach is just fine. Do you know why, or have any scientifical reasoning behind it?