Hello and welcome to HCM forum,
I would be glad to answer your query.
I would like to inform you that whitening mouth wash contains hydrogen peroxide
in it, it is irritating to the oral soft tissues.
These white patches have appeared as chemical burns , but do not worry, it will take a week for them to disappear completely. Do not apply anything over the patches. let them heal on it own.
Avoid using any mouth wash,
Do not eat spicy food until healing occurs.
i hope this answer was useful,
i wish you good health,