I cannot print all images with a nested while loop

i'm newbie on this. I explain shortly what i need. Obtained the category ID via $_GET i want to print how images i have for each product (for that category).

For example, i have 2 product and 2 images for each product.

Problem found: with this code i have printed only the images for the first product and not for the second. Why? Thanks

 $id=17;

  $prod = "SELECT pd_id FROM product WHERE cat_id = ?";
   $stmt = $con->prepare($prod);
     $stmt->bindParam(1, $id);
       $stmt->execute();
         $num = $stmt->rowCount();

    if($num>0)
        {
            while ($row = $stmt->fetch(PDO::FETCH_ASSOC)){
               extract($row);


  $immagini = "SELECT pd_image FROM pd_images WHERE pd_id = ?";
   $stmt = $con->prepare($immagini);
     $stmt->bindParam(1, $pd_id);
      $stmt->execute();

            while ($row = $stmt->fetch(PDO::FETCH_ASSOC)){
               extract($row);
?>                                  
                                        
    <img src="<?php echo $home_url; ?>images/product/<?php echo $pd_image; ?>" class="img-fluid border-radius-0" alt="">
                                        
                                    
<?php 
        }
         } 
          }else { ?>
            <div class="col-lg-12 text-center">
                                <h6>There's no products for this category</h6>
                                     <i class="rt-icon2-user"></i>
                                 <div class="divider-10 d-none d-xl-block"></div>
                            </div>                          
<?php } ?>