Dear Bireshlama I am sorry to hear your baby is poorly. What your baby got is postnasal drip. I think the best thing to do get some normal saline soln (0.9%) and give 1drop in each nosestril every 30 minutes. If the baby is having anti biotics you can stop that as some times antibiotics can make the baby to pass loose stool
. I also advise to stop all medications Make sure the baby gets plaity of fluids.I wish your baby to have speedy recovery. Kindest regards.