langauage web. Ben 3 bağlantıları, Français ... (href = changeLanguage.php? Lang = fr es tr) set

changLanguage.php

session_start();

if(isset($_SESSION['bckTo']) && isset($_GET['lang'])){

    $lang = preg_replace('/[^a-z]/','',trim($_GET['lang']));

    #TODO
    #More vlidation ...

    $full_url = $_SESSION['bckTo']; 
    $full_url = str_replace(array('&lang=en','&lang=es','&lang=fr'),'',$full_url);

header('Location: '.$full_url.'&lang='.$lang.'');
}

$_SESSION['bckTo'] save the current URL for example: mysite.com/index.php?id=x&n_d=y The problem is, the header translate the URL to: mysite.com/index.php?id=x&n_d=y&lang=en.

Herhangi bir fikir takdir edilecektir