Hello, Thanks for the query to H.C.M. Forum. If I were your treating doctor for this case of severe diarrhea I would come up with these possibilities , these includes . 1 Secretory causes are due to derangement in fluid and electrolyte transport across the enterocolic mucosa.Diagnosis can be confirmed by physical as well clinical examination by a gasroenterologist. In this case usually volume of stool is large and large not watery. 2 Carbohydrate malabsorption , diagnosis can be confirmed by examination of lactase as the deficiency of lactase is the main cause . 3 Steatorrheal causes , diagnosis can be confirmed by physical examination of stool because in this case consistency of stool is greasy, foul-smelling difficult to flush diarrhea often associated with weight loss and nutritional deficiency ( as folic acid & vitamin B deficiency in your case) 4 However it is very difficult to mention the causes of diarrhea but few such as factial diarrhea , diarrhea due to other disease such as hyperthyroidism , carcinoid syndrome. TENSION may be the one such cause. In my opinion the best way is to consult a gastroenterologist and get his opinion.Good luck. D.r HET