10 month old baby boy has white coated tongue (not spots) and bad breath. From what I read, probably not thrush, what else could it be?

Could Be Thrush. Frequently, thrush has a white coating over the tongue and if you wipe the tongue gently with a gauze, the classic red "spots" will show up. Either way, you need to have your son evaluated to determine what is causing this. Either a dentist or pediatrician can help you.