Your 18-month-old son has been sleeping through the night for the past two months. you and your spouse were very happy with this new development and were looking forward to many more months of it. but he has started waking up at night again and has been pretty fussy during the day. what is the likely reason that he is waking up now?

His molars are coming in, and he is teething

Explanation:

Early Formation of molars and Teeth tend to occurs between 12-18 months of age. For infants, this process create uncomfortable feeling in their mouth or even a painful sensation.

This pain is what constantly wake the infant up and cry in the middle of the night. The pain will also explain why the infant is acting really fussy during the day. It heavily affect their mood but the infant hasn't develop enough ability to  communicate the problem to the parents.

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