Your digestive system is like a conveyer belt that carries food from your mouth all the way through your body until the waste is excreted. There are many different spots along the way where your system can become inflamed, injured, or blocked. Upper GI issues often cause heartburn and pain or discomfort in the stomach or chest. Problems with the lower GI tract can cause cramping, constipation, or diarrhea.
Source: Verywell Health