Thank you for your question.
I am Dr Saha, I shall try my best to help you.
Black color in midst of normal color can come from food particles or food color.
Bleeding in upper part of GI tract as from peptic ulcer, esophageal varices can turn the stool color black or tarry.
But in those cases, the stool is usually sticky, softer & uniformly colored.
Sometimes, medicines like iron, peptobismol can turn stool black.
However, if the symptom continues, I would suggest to take an examination by doctor & have a stool test.
I hope this information helps.
If there’s anything else I can do, please let me know.
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