The symptoms you have described are suggestive of a condition called malabsorption diarrhea due to certain causes such as lactase deficiency, Giardiasis, Celiac disease, Tropical sprue etc. Lactase is an enzyme that helps us digest milk & milk products. Giardiasis is an infection of the intestine due to a parasite . Celiac disease is a type of abnormal sensitivity to gluten in food such as wheat which can also cause this type of diarrhea. Another possibility is Irritable bowel syndrome but that can be diagnosed if other possibilities are excluded. To begin with I suggest the following tests: Stool microscopy for ova and parasites, Lactose breath test or hydrogen breath test. If the stool shows the presence of Giardia , a suggested treatment is Tinidazole 2g single dose once. If the hydrogen breath test is positive it is suggestive of lactase deficiency. Sometimes transient lactase deficiency can occur in adults. In this case you may lessen your symptoms by avoiding milk and milk products and use substitutes such as soy milk or almond milk etc. The first step would be to see if you have any infectious cause for your diarrhea. If so then that can be treated. If there are no infectious causes in your report you can try by avoiding milk and milk products in your diet and see if that makes a difference. To detect other causes further tests have to be done . In most patients treatment of infections and dietary modifications alleviate symptoms. If symptoms persist you should undergo examination & further investigations in consultation with a gastroenterologist. Best regards