I get black stool once every 20days or a month..it doesn't smell v foul.it happens for one day n color is normal other days..dont take iron med etc?

Possible bleeding: Black stools always rises the concerns about bleeding from the intestines, most commonly from the upper gastrointestinal tract (esophagus, stomach or duodenum), but it could also come from the rest of small bowel and colon. You should seek medical attention and make sure it is not the case. Iron and peptobismol commonly cause black stools as well.