1 of the 5 babies has this white dried out thing sticking out of his butt since 4 days. It was a bit soft and white at first but now it looks dried and yellowish. It also increased in size like its coming outside even more. The baby is 13 days old. His behaviour mostly seems normal although he was dull and was separating himself from the other babies by going into a corner and sleeping and wasnt having much milk from the mother on the day that thing came out. What is that thing?