External cron job firing too many times

You might be calling wp-cron.php every 15 minutes, but your cron task is set to happen every 5 minutes!

    $schedules["5min"] = array(
        'interval' => 5*60,
        'display' => __('Once every 5 minutes'));

...

wp_schedule_event( time(), '5min', 'isa_add_every_five_minutes' );

Change it instead to every 15 minutes

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)