Turn query string to sub page

Put this code in your functions.php–

function the_dramatist_url_rewrite() {
    global $wp_rewrite;
    add_rewrite_tag('%sub%', '([^&]+)');
    add_rewrite_rule(
        '^events/%year%/%monthnum%/%day%/%postname%/?', 
        'index.php/events/%year%/%monthnum%/%day%/%postname%?sub=$matches[1]', 
        'top'
    );
}
add_action('init', 'the_dramatist_url_rewrite', 10, 0);

The go to the permalinks page in the settings menu at dashboard and hit Save Changes button. Hope this is gonna help.