sir ,i am passing black stool for last 20 days but it sometimes seems brown with a milk soured smell and a normal solid stool.sir i have not taken any iron supplemented food or medicine.there is no pain nothing disturbing or uneasiness except mild acidity .please state the reason and homely remedies if there.age :32,height:5.4,weight:72 ,habit:irregular and untimely diet,smoking,drinking alcohol.