I concur with Saitana - blue lips is most likely cyanosis, which means he's not getting enough oxygen. Mottled and cold extremities - thermal problem, or circulation problem - In adults, I'd assume hypothermia, but I doubt he's been out in the bush...

But yes, get thee in contact with a pediatrician, and/or try warming gently. Check for any gurgling/coughing or wheezing that may be lung congestion causing the cyanosis.