Problems with has_post_thumbnail

Probably a little too drunk to be posting code right now, but maybe this will hep you out:

//Previous Post in Category
function get_prev_cat_post($categoryID) {
    global $wpdb, $post;

    // get post date of current post
    $currentPostDate = $post->post_date;
	$newPostInfo = $wpdb->get_row(
		"SELECT * FROM $wpdb->posts
		LEFT JOIN $wpdb->term_relationships ON
		($wpdb->posts.ID = $wpdb->term_relationships.object_id)
		LEFT JOIN $wpdb->term_taxonomy ON
		($wpdb->term_relationships.term_taxonomy_id = $wpdb->term_taxonomy.term_taxonomy_id)
		WHERE $wpdb->posts.post_status = 'publish'
		AND $wpdb->posts.post_type = 'post'
		AND $wpdb->term_taxonomy.taxonomy = 'category'
		AND $wpdb->term_taxonomy.term_id = $categoryID
		AND $wpdb->posts.post_date < '$currentPostDate'
		ORDER BY post_date DESC
		LIMIT 1");     

	if ($newPostInfo) {
		return $newPostInfo;
	}
}

//Next Post in Category
function get_next_cat_post($categoryID) {
    global $wpdb, $post;

    // get post date of current post
    $currentPostDate = $post->post_date;
	$newPostInfo = $wpdb->get_row(
		"SELECT * FROM $wpdb->posts
		LEFT JOIN $wpdb->term_relationships ON
		($wpdb->posts.ID = $wpdb->term_relationships.object_id)
		LEFT JOIN $wpdb->term_taxonomy ON
		($wpdb->term_relationships.term_taxonomy_id = $wpdb->term_taxonomy.term_taxonomy_id)
		WHERE $wpdb->posts.post_status = 'publish'
		AND $wpdb->posts.post_type = 'post'
		AND $wpdb->term_taxonomy.taxonomy = 'category'
		AND $wpdb->term_taxonomy.term_id = $categoryID
		AND $wpdb->posts.post_date > '$currentPostDate'
		ORDER BY post_date ASC
		LIMIT 1");

	if ($newPostInfo) {
		return $newPostInfo;
	}
}

//Previous & Next Post Navigation with images.
function get_navHTML() {
	$navHTML = '';
	if(function_exists('get_prev_cat_post') && function_exists('get_next_cat_post')) {
		$featuredID = get_category_by_slug('featured')->term_id;
		$slideshowID = get_category_by_slug('slideshow')->term_id;
		$portfolioID = get_category_by_slug('portfolio')->term_id;
		$excludedCats = array($featuredID, $slideshowID, $portfolioID);
		foreach (get_the_category() as $category) {
			if (!in_array($category->cat_ID,$excludedCats)) {
				$mainCatID = $category->cat_ID;
			}
		}
		$mainCat = get_cat_name($mainCatID);

		$prev = get_prev_cat_post($mainCatID);
		$prevID = $prev->ID;
		$prevTitle = $prev->post_title;
		$prevURL = get_permalink($prevID);
		$image = get_post_meta($prevID, 'photoQImageSizes', true);
		if($image){
			$prevThumb = $image['tiny']['imgTag'];
		}elseif(has_post_thumbnail($prevID)) {
			$prevThumb = get_the_post_thumbnail($prevID,'thumbnail');
		}
		$next = get_next_cat_post($mainCatID);
		$nextID = $next->ID;
		$nextTitle = $next->post_title;
		$nextURL = get_permalink($nextID);
		$image = get_post_meta($nextID, 'photoQImageSizes', true);
		if($image){
			$nextThumb = $image['tiny']['imgTag'];
		}elseif(has_post_thumbnail($nextID)) {
			$nextThumb = get_the_post_thumbnail($nextID,'thumbnail');
		}
		if($prev || $next){
			$navHTML .= '
			<nav class="nav-single">
				<h6><a href="'. get_category_link($mainCatID) .'" title="'. $mainCat .'">More from <em>'. $mainCat . '</em></a></h6>
				<ul>';
					if($prev){
						$navHTML .= '
						<li class="older">
							<a href="' . $prevURL . '" title="' . $prevTitle . '">
								<span class="nav-image">' . $prevThumb . '</span>
							</a>
						</li>';
					}
					if($next){
						$navHTML .= '
						<li class="newer">
							<a href="' . $nextURL . '" title="' . $nextTitle . '">
								<span class="nav-image">' . $nextThumb . '</span>
							</a>
						</li>';
					}
				$navHTML .= '</ul>
			</nav>';
		}
	}
	return $navHTML;
}