load PHP from JavaScript

I'm doing a game in JavaScript and the result, when we win or lose, I pass it to a database with PHP. It is limited to making an update +1 query in games and +1 in wins or losses, and depending on whether we win or lose is a PHP file or another.

I am trying to do it for AJAX but it does not load the script. Look to see if you can lend me a hand.

The AJAX part:

function ganar() {
var enviar = new XMLHttpRequest();
  var relleno = 123;
  var url = 'ganar.php?relleno=' + relleno;

  enviar.open('GET', url, true);
  enviar.send(null);
  alert("HAS PERDIDO");
  window.location.href = "../charmander/perfil.php";
}
/***********************************************************/

The PHP:

<?php

$nombre=$_SESSION['usuario'];


$base= new PDO('mysql:host=localhost;dbname=te_la_juegas','root','');

$base->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);

$base->exec("SET CHARACTER SET UTF8");

$sql="UPDATE USUARIOS SET partidas = partidas + 1, partidas_ganas = partidas_ganas + 1
 where nombre like '$nombre' ";
$resultado=$base->prepare($sql);

//$resultado->bindValue(":nombre",$nombre);

$resultado->execute(array($nombre));

header('Location:http://localhost/TRABAJO_FINAL/registrado/charmander/perfil.php');
exit;

 ?>