What is this?

my 2 month old son's tounge, inner cheeks, and inside of his bottom lip are white and look sort of blistered. noone goes near his mouth and i sterilize his bottles, , and pacifiers every night. what could this be and what can i do for it? i called his pediatrician and they cant get me in until tuesday. he doesnt act like it is bothersome or painful, it is just disturbing me because it came about all of a sudden.