Dark brown baby poo

[Pieorcrumble]

Evening! Any poo experts here? My 4 month old baby (breast fed with a very occasional bottle of formula) has just done a really unusual poo. It's the colour of dark chocolate - much much darker than his usual mustard coloured poos.

He seems well in himself but google is making me worried that there's something wrong, and that he might be bleeding?!

He has recently started pooing less frequently (every few days) and his farts are now smellier than before, but the colour has, until now, looked normal.

Has anyone experienced similar? Should I be worried?

Thanks and sorry for the gross post (I have a photo if anyone wants me to take the grossness up a notch!).

Odd enough I don't remember any change of colour like that until food was introduced, could someone have slipped him some food?

Have you eaten anything different to normal?

No he's definitely not had any food, just breast milk. He's not even had formula for a few days and even then only one bottle before bed. My diet hasn't changed either.