Although the cause of functional bloating remains unknown, old explanations such as a low diaphragm, exaggerated lumbar lordosis, and psychiatric problems have been disproved. [ncbi.nlm.nih.gov]

The patient also had a significant history of chronic constipation that had begun approximately 10 y prior to her experiencing the daily abdominal pain. [ncbi.nlm.nih.gov]

It can cause discomfort and abdominal pain. In some cases, abdominal bloating and pain can occur due to a serious problem. [healthline.com]

Bacterial fermentation within the large intestine causes gas, upper abdominal bloating and abdominal pain. Treatment of lactose intolerance may include dietary restriction and ingestion of synthetic lactase supplements. [livestrong.com]

RESULTS: Approximately 50% of irritable bowel syndrome patients with bloating also experience an increase in abdominal girth and this is more pronounced with constipation than diarrhoea. [ncbi.nlm.nih.gov]