first off try clearing any plugin / server caches you have.
If it is still doing it then you its possibly an incorrect database table prefix in your wp-config file. If you are not sure about this then best to contact your host and explain the issue. They should be able to help you resolve.
I don´t have any cache plugin working on the site, and table prefix is fine in database and wp-config.php. Maybe trying to restore the site might be a solution, but it´s strange as web didn’t do any changes on the site for a couple of weeks, and no WordPress updates or plugins.