I got this from searching on the web:
In newly constructed homes it is common to see nails/screws popping through drywall. This is due to the wood studs and joists having a high moisture content when a house is constructed rapidly (the old "time is money concept") and the drywall is applied to the studs before they have had any time to dry. Studs will dry out within the wall space and when this happens dry wall screws can pop as a result.
Moisture could be causing the nails popping out, especially if they are corroded. What I would be most concerned is hidden mold growing behind the dry wall. You need to check and see what might be causing the problem first.
Questions to ask:
How is Your Family's Health?
Does anyone have allergies or asthma?
Does anyone in your home always seem to have a cold-a runny nose, wheezing, coughing, and headaches?
Do these problems go away when they leave home for a while?
Are there infants, children, or elderly people living in the household?
How Can You Tell if Mold is Growing in Your Home?
Can you see mold growing anywhere?
Is there mildew growing on clothes or towels?
Does any part of your house or apartment smell musty or moldy?
Do you see color changes on walls or floors that you can't wipe off?
Is There Moisture in Your Home That Could Cause Mold to Grow?