When you take your dam in for her post whelp exam (24 hours after whelp) take that pup with you so they can try and find out what the problem is and what can be done. It could be that there's still fluid in the lungs, aspiration (they will check for possible cleft palate as that interferes with ability to eat) and obvious infection and things. Hope your baby's are okay (including mom).
www.dogfoodanalysis.com
www.dogfoodanalysis.com