Some more details are required, viz: -
Birth weight of the baby
Current weight & length of the baby
The quantity and frequency of the formula feeds
The quantity and consistency of the stools
Is the baby being breast
If the stools are not very watery and if the quantity is not very large, you need not worry.
You can add Zinc
syrup to the medicine given by your Doctor
Please be sure that strict hygiene is observed while formula feeds are being given (hand
washing, sterilization of feeding bottles after every feed, adequate boiling of water being used to reconstitute the formula.