Hi, you are probably suffering from cholecystitis or cholelithiasis(inflammation of gall bladder and Gall stones). Normally Gall bladder stores & concentrates BILE (specially secreted fluid from liver which contains biliary pigmentes called bilirubin and biliverdin, bile is green in color). Gall bladder also secretes bile salts and bile acids. Bile along with its salts is required for digestive process in small intestine; bile salts are required for digestion of fat components of food and metabolism. In conditions such as cholecystitis or cholelithiasis when your gall bladder is not working adequately, it doesn t stores and concentrates bile, large amounts of bile flows straight through your GI system giving your stools green color. Apart from this eating foods containing too much chlorophyll can also give stool a green color. E.g. Spinach