Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advise. A very common and possible cause of the diarrhea is giardia. This is a microscopic parasite that may cause diarrhea for a long time and the stools float. You may get bad frothy smell as well. To diagnose it you may have a stool test for ova and parasite and if this does not find it (it may not find giardia in many patients that have it, but if it is found with this test than you don t need further tests), then you might need to do a stool antigen test for giardia which is more accurate. If this test is not done in your country than just take Metronidazole three times a day for 7 days. Another possible cause is malabsorbtion. This can be to milk intolerance so please try to get yogurt and cheese but avoid milk for 2-3 weeks and see if there is a difference. Lack of pancreatic enzymes is another possible cause in some cases and taking pancreatic enzymes in pills may help. Rarely gluten intolerance can be the case and there is a blood test that can be done for this if all of the above don t seem to address it. Hope I have answered your query. Let me know if I can assist you further.