Just to check, if lo is having fever, do we put them in air con room or room with fan? Wearing long sleeve and long pants with socks.

I will not let them wrap long sleeve and long pants. Better to go with something light and airy. You don't want to trap the heat. Best to put in a room with fan, or at least cool air. Try taking your bub outdoors and get him to sweat. It really helps. Be careful if temperature gets too high.