Hi, Thank you for your query. I can understand your concerns. Fat malabsorption (Steatorrhea) usually causes greasy, foul-smelling, stool. Combination with upper abdominal pain points towards Chronic pancreatitis, (commonly a sequel of alcohol abuse) leading to pancreatic exocrine insufficiency. Prevacid (lansprazole) alone may not be sufficient. Pancreatic enzymes supplementation has to be added. Other possibilities: Bacterial overgrowth in the small intestine may deconjugate bile acids and alter micelle formation, impairing fat digestion; it occurs with stasis from a blind-loop, small-bowel diverticulum or dysmotility and is especially likely in the elderly. Celiac disease( gluten-sensitive enteropathy) can present with fatty diarrhea associated with many other GI manifestations including abdominal pain,mimicking irritable bowel syndrome. Several other conditions may cause mucosal malabsorption/fatty diarrhea including infections, especially Giardia, amyloidosis & chronic ischemia. You need to undergo detail evaluation to come to a correct diagnosis & subsequent management will follow accordingly. Regards Dr. T.K. Biswas M.D. Mumbai