Hello, Thanks for the query to H.C.M. Forum. If I were your treating doctor for this case of severe weight loss within 2 years , I would come up with these possibilities , these includes. 1 Depression , this is the ,most important cause of weight in elderly patient without any significant reason . Diagnosis can be confirmed by physical as well clinical history of patient by a psychiatrist. As you mentioned that all tests are normal including blood work, so chance of depression is there. 2 Cancer of intestine as you mentioned that previously you were a patient of constipation and now 4-5 motions/day with soft stool . Change of intestinal habit is an important factor and an indication of cancer . Diagnosis can be confirmed by colonoscopy examination . 3 Benign gastrointestinal disease . Diagnosis can be confirmed by ultrasound and M R I of abdomen . In my opinion deal according to above mentioned reasons . Good luck. Dr. HET