Have any of the doctors you've seen run a fecal sample test for Pancreatic Elastase? If not, you might want to push for one. Collecting the sample isn't fun but worth it to find out if you have low pancreatic enzymes. If yours are low, you would not be able to digest food and your symptoms - especially the greasy stools - align with what I know of this condition. I was diagnosed after sudden onset of diarrhea, weight loss, fatigue after a bout of food poisoning. Stool samples were taken and along with a diagnosis of microscopic colitis, it was found I had severely low pancreatic enzymes (34 - normal level is 200. I started Creon in November and it has been a total game changer.