Hello, Black coloured stools with a strong odour are usually due to a bleed which is happening high above in the food tract. As it passes down to the end of the tract which is the anus, the blood cells break down due to digestive juices and enzymes resulting in the black colour. So the child need to be clinically examined for any bleed. Anemia which a physician can assess by examining the paleness of the child s eye, palm and nails is a strong indicator of blood loss. Consumption of certain iron supplements, Ragi(a type of millet) can also result in black stools. Methylphenidate which is the generic name for Concerta can cause black stools too, but very rarely. It is usually an emergency situation if the stool is black due to blood loss, so i recommend you consult with a physician immediately to rule it out. I hope I answered your query. Thank you.