Do you get that message here or on other wikis? Because generally that's a sign that there was a message deleted on a board that you are following. If you want to get rid of those notifications, you can click "mark all as read".
I had it happening yesterday as well, but as said, that was because a message was deleted from my wall. If this keeps happening and it's not from deletion, then I'd contact FANDOM Staff and file a bug report.