My 13 year old child having black poop and not in shape is getting pea sized thing in his poop he his having stomache ache in lower side also he is having very black poop sometimes and indegistion gas making also?

The biggest concern with black stools is that there may be bleeding in the stomach or intestines. You should take him to the doctor to check. However, it can be black from taking iron supplements or eating licorice, blueberries or something called blood sausage. The small size and the indigestion gas are typical of constipation. Again at 13, he should see a doctor for this.

Solid black stool, particularly if it is foul smelling and tarry, can be a sign of internal bleeding. If the stool is black, he should be seen by his primary care doctor or in the emergency room. Good luck.