Thank you for your query on Healthcare Magic.
Green color stool is a normal variant in infants.
If the stool is not foul smelling, not watery, and not associate wit mucus and blood , not associated with increased frequency, nothing to worry.
But exclusive breastfeeding
till the age of 6 months is the best method of feeding.
The dark green color of the stool may be due to rapid passage of stool in the gut or a normal variant.
Hope I have answered your query.