Helloo my baby when was born was 3.2 kg and now is 1 and half months old and 4kgs He was only on breast milk but has not gained much weight so the doctor said to add formula milk in a day but as soon as we give him formula milk he poops .. whereas on breast milk he used to not poop for even 5-7 days after 25 days of his birth so i want to know is it normal ??