voice change?

Joanna • instagram/facebook:yanncandy
My 7 month old boy has this voice three days now as if he got a cold. He has not a flu or fever or anything that shows he got a cold but he has that raucous voice
Doc said to sit him over steam and keep him in fresh air rooms
Others say it might be. Voice change
I live in the city though and i am afraid that the air is polluted no matter how i try to refresh the house
Did you see any difference to yor bbs voices?