There are many different causes/reasons- it is not always because there is something wrong with the stomach.
Possible Reasons
Medications - Opioids, Ibuprofen/NSAIDs, Steroids antibiotics, vitamins and supplements
Pain can cause the gut to work less well
Anxiety
Gut issues - reflux/heartburn, stomach inflammation, constipation
Metabolic imbalances
Excess mucous/secretions
Headaches
