Visible movement in stomach

I've noticed my stomach moving lately. After I eat, and get bloated, I lift my shirt and look down at my stomach. It shifts and jerks back and forth, like contractions or something moving around. It is very noticeable, but not as noticeable as visible peristalsis.

I rarely feel the movements, but sometimes have sudden, short pains, or pulling sensations in my colon. I have some issues with constipation, which I sometimes take stuff for, and can still have a bm at least every other day.

My girlfriend is worried and thinks I should see a doctor. Has anyone experienced this, or heard of it? I searched online but didn't find much.