There are multiple causes for abdominal pain for a person who is in his 20’s, but when you find the combination of abdominal pain, with black stools, then the cause for this particular thing can be cut down to a smaller list of diagnosis. Like very common reason why a person can have blackish stools is because he is on too much iron supplements .that is very commonly seen that in people who are taking iron supplements complain that their stools have become very black, sticky. It also happens by taking certain fruits like blackberries, then the stools can become blackish. His is natural and normal and need not worry about it. That is called as false melena. Melena is blackish stool, where you find blood in stools and when the blood is from the upper part of the intestinal tract, then by the time it reaches the rectum and comes out in the form of stools, it turns blackish. Now, if it is due to supplements and due to medicines, then it is not blood and that is why we call it as false melena. But in real melena, there are few causes which can cause this. That is, if you have an ulceration, even gastritis can cause slight erosions and there can be blood in the stools which is blackish in colour. If there are some varicose ulcers on the lower end of the oesophagus, that can rupture the food pipe, foodpipe can rupture, and then that can cause blood in the stools. In people who have severe vomiting sometimes there can be a tear of oesophagus. This is called as Vallerie waste air and that can cause melena. So the pain in the abdomen can be related to any of these things. So if these factors are there, there can be blackish stools and can have pain in the abdomen.