4yr old had tonsillectomy. has a grey/whitish coating on tongue. also bad breath. is this normal?

Infection: Often when there is surgery in the mouth there is an odor associated with it. Just to be sure have your child checked for an infection.

Thrush: You would want to let your surgeon know, but one of the more common causes is thrush. Antibiotics given at the time of surgery can kill bacteria normally found on the tongue. This can then lead to an overgrowth of Candida albicans, which is a yeast and makes the tongue appear white. It is usually taken care of with a prescription mouth wash called nystatin swish and swallow.