Why do my lo keep putting his fist in his mouth and sometime he vomited after too much sucking of fist. He is 3 months going to 4 months soon. Any mummies encounter this? He vomit out all his milk he drank like 20 mins earlier. I don't know how to stop him from vomiting. Mummies pls advice...

Some babies like to suck fingers, some don't and some like to suck whole fist. You can only try to keep pulling his fist out and stop him from putting it in. Have you given him any teether before? Babies usually need something in their mouth to soothe themselves at this age. Try the banana teether.