5. Indigestion
Indigestion is the result of an inability to properly digest the food, which can cause some of that food to travel back up through the oesophageal sphincter along with stomach acids. This causes reflux and heartburn and can be very painful and unpleasant.
This can happen whenever any kind of food is not properly digested and that in turn might mean that you experience these symptoms when struggling with lactose intolerance.