Hi...a 4 days old new born baby cannot be administered antibiotics like this without proper evaluation and proper blood and urine cultures. 4 days old baby having a jaundice of 14.6% could as we be physiological jaundice. But it needs follow up with at least 24 hours once checking of bilirubin levels. Netilmicin is an antibiotics of the class of Aminoglycosides. Colistop is a medicine which will temporarily relieve pain abdomen. But it is not routinely indicated. The diarrhea you kid is having could as well be a gastrocolic reflex. This need not be treated as diarrhea and especially antibiotics are not indicated. When the baby takes milk , the stomach expands - then when it is contracting it sets off a wave form which moves down the intestines and when that wave reaches the lower down rectum, a small quantity of the stool is evacuated out. This is the basis for gastro-colic reflex. Do not worry. Unless the kid s having low urine output or very dull or excessively sleepy or blood in motion or green bilious vomiting...you need not worry. Regards - Dr. Sumanth