*Poo in Nappy*

Hi all, my daughter has had a few of these black poos and we’ve called the GP but they’ve just said that because she has no other symptoms (she’s well in herself) they’re not concerned. I took in a sample and they cleared it of blood; she eats nothing that would have turned her poo this colour. I asked if it’s possible that her stool sample was a false negative and should we do another, and was told no; the test is so sensitive it would pick up the most minuscule traces of blood so I should be confident that the black is not blood. Does anyone else’s toddler ever have stools this colour? I’m understandably very concerned - Thank you x