Dark brown stool is it blood?

could be or you ate spinach. Check it out. At your age unlikely to be blood.

Not always, definitely what we fear the most. Specific foods, supplements or drugs can darken the stool aside from a gastrointestinal hemorrhage.

If you have any concern about it being blood, you can buy a kit at the pharmacy to test fo it. Visit this site for abnormal colored stool: https://www.mayoclinic.org/stool-color/expert-answers/faq-20058080 Wish you good health!