Gastro intestinal issues affect your gastrointestinal (GI) tract from mouth to anis.
There are two types: functional & Structural e.g colitis, food poisoning, lactose intolerance and diarrhea.
Many factors can upset your GI tract and its motility (ability to keep moving) including:
Eating a diet low in fiber
Not getting enough exercise
Travelling or other changes in routine
Eating large amount of dairy products.
Stress
Resisting the urge to have a bowel movement.