kdurrum

I have narrowed my issue down to this set of code:

$post_id        = $posts[$j]->ID;
				setup_postdata($posts[$j]);
				$excerpt        = get_the_excerpt();
				$attachment_url = wp_get_attachment_image_src( get_post_thumbnail_id($post_id), 'full' );
				$url            = $attachment_url['0'];
				$image          = aq_resize($url, $thumb_width, $thumb_height, true);
				$mediaType      = get_post_meta($post_id, 'tz_portfolio_type', true);
				$prettyType     = 0;

				if ($count > $columns) {
					$count = 1;
					$output .= '<ul class="posts-grid row-fluid unstyled '. $custom_class .'">';
				}

				$output .= '<li class="'. $spans .'">';
					if(has_post_thumbnail($post_id) && $mediaType == 'Image') {

						$prettyType = 'prettyPhoto-'.$rand;

						$output .= '<figure class="featured-thumbnail thumbnail">';
						$output .= '<a href="'.$url.'" title="'.get_the_title($post_id).'" rel="' .$prettyType.'">';
						$output .= '<img  src="'.$image.'" alt="'.get_the_title($post_id).'" />';
						$output .= '<span class="zoom-icon"></span></a></figure>';
					} elseif ($mediaType != 'Video' && $mediaType != 'Audio') {

						$thumbid = 0;
						$thumbid = get_post_thumbnail_id($post_id);

						$images = get_children( array(
							'orderby'        => 'menu_order',
							'order'          => 'ASC',
							'post_type'      => 'attachment',
							'post_parent'    => $post_id,
							'post_mime_type' => 'image',
							'post_status'    => null,
							'numberposts'    => -1
						) ); 

						if ( $images ) {

							$k = 0;
							//looping through the images
							foreach ( $images as $attachment_id => $attachment ) {
								$prettyType = "prettyPhoto-".$rand ."[gallery".$i."]";
								//if( $attachment->ID == $thumbid ) continue;

								$image_attributes = wp_get_attachment_image_src( $attachment_id, 'full' ); // returns an array
								$img = aq_resize( $image_attributes[0], $thumb_width, $thumb_height, true ); //resize & crop img
								$alt = get_post_meta($attachment->ID, '_wp_attachment_image_alt', true);
								$image_title = $attachment->post_title;

								if ( $k == 0 ) {
									if (has_post_thumbnail($post_id)) {
										$output .= '<figure class="featured-thumbnail thumbnail">';
										$output .= '<a href="'.$image_attributes[0].'" title="'.get_the_title($post_id).'" rel="' .$prettyType.'">';
										$output .= '<img src="'.$image.'" alt="'.get_the_title($post_id).'" />';
									} else {
										$output .= '<figure class="featured-thumbnail thumbnail">';
										$output .= '<a href="'.$image_attributes[0].'" title="'.get_the_title($post_id).'" rel="' .$prettyType.'">';
										$output .= '<img  src="'.$img.'" alt="'.get_the_title($post_id).'" />';
									}
								} else {
									$output .= '<figure class="featured-thumbnail thumbnail" style="display:none;">';
									$output .= '<a href="'.$image_attributes[0].'" title="'.get_the_title($post_id).'" rel="' .$prettyType.'">';
								}
								$output .= '<span class="zoom-icon"></span></a></figure>';
								$k++;
							}
						} elseif (has_post_thumbnail($post_id)) {
							$prettyType = 'prettyPhoto-'.$rand;
							$output .= '<figure class="featured-thumbnail thumbnail">';
							$output .= '<a href="'.$url.'" title="'.get_the_title($post_id).'" rel="' .$prettyType.'">';
							$output .= '<img  src="'.$image.'" alt="'.get_the_title($post_id).'" />';
							$output .= '<span class="zoom-icon"></span></a></figure>';
						}