$_SERVER["HTTP_REFERER"]
<?php
$return="";
if ($_SERVER["HTTP_REFERER"] && strpos($_SERVER["HTTP_REFERER"], "pagina.php")!==false) {
$return=$_SERVER["HTTP_REFERER"];
setcookie("lastUrl", $_SERVER["HTTP_REFERER"], 0);
} elseif (isset($_COOKIE["lastUrl"])) {
$return=$_COOKIE["lastUrl"];
}
...