It is common for newborns to have nasal congestion, even if they are not cold, in this period is also common for the baby sneeze and cough.
The problem is that the baby is feeding, either bottle or breast, you have to suck through the mouth while breathing through your nose, if it is congested you can not do and try to breathe through the mouth, choking him to stop cause drink milk may harm their receiving no food.
The causes may be environmental, it should review the nursery, make sure it is properly ventilated, that you are not using air fresheners, that no cigarette smoke, etc. If you live in a place with high humidity, will have to purchase a dehumidifier.
To help resolve nasal congestion in newborns should eliminate any environmental factor that may be causing it, also make a nasal cleaning with gauze and water on the outside of each nostril. You can also suck the nasal aspirator (bulb), if the mucus is too thick, place a few drops of saline in each nostril to loosen the mucus.
To relieve the discomfort of nasal congestion hold the baby upright, keeping your head up, because nasal congestion is worse when lying down.
Do not use nasal decongestants and anti histamines unless prescribed by your doctor.