try get_pages with
'child_of' => get_the_ID(),
'parent' => get_the_ID(),
If you need i can post full code
EDIT :
if ( is_singular('post') ) {
$args = array(
'post_type' => 'attachment',
'posts_per_page' => -1,
'post_status' => null,
'parent' => $post->ID ,
'child_of' => $post->ID,
'sort_order' => 'desc'
);
$attachments = get_pages( $args );
if ( $attachments ) {
foreach ( $attachments as $attachment ) {
echo wp_get_attachment_url( $attachment->ID );
}
}else {
}
}
I hope this code help you