When you get “stopped up,” you can feel bloated. Mostly, it happens when you need water, fiber, or exercise. But diet changes, illness, or stress also can do it. It usually passes, but exercise, water, and over-the-counter meds can help. See a doctor if you're losing weight and don't know why, it lasts more than a week or two, or you have dizziness, belly pain, or blood in your stool. These could be signs of something more serious.