使用http_build_query增加页面查询？

I've got a Wordpress instance running on Server 2012. I can't install the http_build_url. I'm trying create a link that will increase the page query while preserving and other querys that exist in the url. Here's what I've got so far (which doesn't work, the rebuilt URL doesn't include any of the queries from the original url). It also doesn't work if the user is on the first page because page doesn't exist in the array.

EDIT: $user_query is initialized at the time the code is executed.

Thanks for any help!

<?php
$query=$_GET;
$query['page']=$user_query->current_page+1;
$url=$_SERVER['PHP_SELF']. '?' .  http_build_query($query);

?>
<a href="<?php $_SERVER['REQUEST_URI'] . '?' . $url; ?>">More Pages</a>