Your mother has some form of maldigestion/malabsorption and needs to be evaluated by a gastroenterologist for pancreatic dysfunction and mucosal malabsorption. She will need specialised tests which may include faecal elastase, abdominal ultrasound, faecal chymotrypsin, stool fat estimation, ERCP/MRCP (not all these tests will be needed and a certain combination will yield a diagnosis. If the pancreatic function tests are normal, she should have a small bowel biopsy.