my baby is 3 month old he passes stool 4 times a day but sometimes he passes dark green stool but other time normal yellowish

A. Green poop may indicate a foremilk/hindmilk imbalance in breastfed babies, which results in your baby is getting a larger portion of foremilk (watery milk) than hindmilk (thicker, fattier milk). Though this can cause tummy discomfort, it doesn't indicate a milk supply issue or problem with your milk.