Pediatritian, NOW. While it may not be an emergancy, any change in temp with infants is highly worrisome, especially the fact he's blue to the lips and cold to the touch, he may have an upper respetory infection and not getting enough air, he might also simply be too cold (it is winter) and needs more warmth.

A pediatrician can give you more info.

(Note: Not a mum but those were classic signs to look for in my First Aide classes - Former Nanny)