Wordpress Next/previous links with thumbnails and excerpts

<div class="navigation">
    <div class="nav-newer clear-fix">
        <?php $nextPost = get_next_post(); if($nextPost): ?>
            <?php if (has_post_thumbnail( $nextPost->ID ) ): ?>
                <?php $nextthumbnail = wp_get_attachment_image_src( get_post_thumbnail_id($nextPost->ID), 'secondary-thumb' ); $nextthumbnail = $nextthumbnail[0]; ?>
            <?php else :
                $nextthumbnail = get_stylesheet_directory_uri() . '/images/default-featured.jpg'; ?>
            <?php endif; ?>
            <div class="thumb" style="background-image:url(<?php echo $nextthumbnail; ?>);"><a href="<?php echo get_permalink(get_adjacent_post(false,'',false)); ?>"></a></div>
            <div class="entry">
                <div class="label">Next post</div>
                <h4><?php next_post_link('%link'); ?></h4>
                <p><?php setup_postdata( $nextPost ); the_excerpt(); ?></p>
            </div>
        <?php endif; ?>
    </div>
    <div class="nav-older clear-fix">
        <?php $prevPost = get_previous_post(); if($prevPost): ?>
            <?php if (has_post_thumbnail( $prevPost->ID ) ): ?>
                <?php $prevthumbnail = wp_get_attachment_image_src( get_post_thumbnail_id($prevPost->ID), 'secondary-thumb' ); $prevthumbnail = $prevthumbnail[0]; ?>
            <?php else :
                $prevthumbnail = get_stylesheet_directory_uri() . '/images/default-featured.jpg'; ?>
            <?php endif; ?>
            <div class="thumb" style="background-image:url(<?php echo $prevthumbnail; ?>);"><a href="<?php echo get_permalink(get_adjacent_post(false,'',true)); ?>"></a></div>
            <div class="entry">
                <div class="label">Previous post</div>
                <h4><?php previous_post_link('%link'); ?></h4>
                <p><?php setup_postdata( $prevPost ); the_excerpt(); ?></p>
            </div>
        <?php endif; ?>
    </div>
</div>