Display Date Below Day of Week in Header

Greetings! Hope you're doing well...
I just updated the Appointments+ plugin and lost my "functions.php" filter ability to add the mm/dd below the day of the week, on my weekly calendar. Here's my functions.php filter...

// Appointments+ Modification to add date below Day
// Filtering weekly thead
function app_filter_weekly_head ($head) {
	global $appointments;
	$short_day_names = $appointments->arrange($appointments->get_short_day_names(), false);
	$base_time = !empty($_GET["wcalendar"]) && is_numeric($_GET["wcalendar"])
		? $_GET["wcalendar"]
		: $appointments->local_time
	;
	$base_week_time = $appointments->sunday($base_time) + ($appointments->start_of_week * DAY_IN_SECONDS);
	foreach ($short_day_names as $idx => $day) {
		$date = date_i18n($appointments->date_format, $base_week_time + ($idx*DAY_IN_SECONDS));
		$date = date('m/d',strtotime($date)); // date('jS',strtotime($date));
		$head = preg_replace('/' . preg_quote("<th>{$day}</th>", '/') . '/', "<th>{$day}<br /><span class='showdate'>{$date}</span></th>", $head);
	}
	return $head;
}

add_filter('app_schedule_before_first_row', 'app_filter_weekly_head');
// END APPOINTMENT FILTER