Wa'alaikumassalam sis! Diarrhea dalam babies memang scary, tapi kena tengok dulu, kalau fresh milk ke formula ke, ada babies yang intolerant atau sensitive sikit je. 3-4 kali sehari dalam 3 hari tu dah boleh dehydrate, so kena monitor wet diapers dia and colour of urine (should be clear or pale yellow). Tips dari my experience: offer breastmilk lebih kerap atau oral rehydration solution macam Pocari if dia formula fed, kurangi solid food sebentar, and tengok kalau ada other symptoms macam fever atau rash. Tapi honestly this needs a doctor check-up sis, kena tahu sebab dia first, could be infection, allergy, atau teething, and depending on berapa umur dia. Jangan delay, better safe than sorry with diarrhea in babies!