Programmer - PHP Switch Nav system - how can i set it up to use 2 GET variables

Programmer Question

I use a the following PHP switch for my navigation menu:

<?php include("header.php"); 
    if (! isset($_GET['page']))
    {
        include('./home.php');

    } else {    
        $page = $_GET['page'];  
        switch($page)
        {
            case 'about':
                include('./about.php');
                break;  
            case 'services':
                include('./services.php');
                break;  
            case 'gallery':
                include('./gallery.php');
                break;      
            case 'photos':
                include('./photos.php');
                break;  
            case 'events':
                include('./events.php');
                break;  
            case 'contact':
                include('./contact.php');
                break;
        }
    }
    include("footer.php"); 
    ?>

When I go to my "Photos" section, I am going to have a sublist for other galleries within the photos.

When I am on a page right now, my url looks like this:

index.php?page=photos

I would like to know what PHP code I need to add so when i go to the CARS section I can have my url look like this:

index.php?page=photos&section=cars

?