Sounds like intestinal bleeding perhaps from a peptic ulcer. Definitely take them to the hospital!

I agree with the above. Black tarry stools are often a sign of gastrointestinal bleeding and should be dealt with by a physician quickly.

my brother had that and thought thats what it was but it turned out to be the pepto bismol in his case, so if youve dranken quite a bit of that it can have the same effect but i think either way going to the ER is safest.