Reblogging this as a lot of my clients have chronic illness of one form or another and most of them have told me that at least one of the things you list is what really winds them up.
Please check that this widget Facebook Reviews has a connected Facebook.
Facebook API Error: {"error":{"message":"Error validating access token: The user has not authorized application 1501100486852897.","type":"OAuthException","code":190,"error_subcode":458,"fbtrace_id":"AC0JjpOCZMlzZ7vN8M3f-zT"}} Reconnecting to Facebook may fix the issue.