Subsite taking over the parent site

I have a multisite installation with 3 subdomains, one for the main site (no ID, but wp-config refers to this as 1), one for blog site (ID 5), and the other for a training site (ID 3).

Since last week, my users have been complaining that the main site is gone when they type cantilin.com (swap a for e). Instead, it’s now replaced by the blog site. And when I try to visit the blog.cantilin.com and training.cantilin.com, it’s all being mapped to the original blog site.

Configuration of wp-config is as follows:

define( 'MULTISITE', true );
define( 'SUBDOMAIN_INSTALL', true );
$base = '/';
define( 'DOMAIN_CURRENT_SITE', 'centilin.com' );
define( 'PATH_CURRENT_SITE', '/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );

The only possible reason I can think about is this code snippet that I placed on the main site to grab post content from the blog site.

add_shortcode('blog-posts', 'blog_posts');
function blog_posts($atts) {
	extract( shortcode_atts( array(
		'no' => '',
		'id' => '',
	), $atts ) );

	if($id == '') {
		$output = 'Invalid Blog ID. Unable to retrieve posts';
		return $output;
	} else {
		if ( false === ($output = get_transient('msblog_outputs')) ) {
			switch_to_blog($id);
                	$posts = get_posts("showposts={$no}");
                	$output = '';
                	if ($posts) {
				$output = '<ul class="blog-posts">';
				foreach ($posts as $post) {
					$post->post_title = apply_filters( 'the_title', $post->post_title );
                               		$output .= '<li><a href="' . get_permalink($post->ID). '" title="' . $post->post_title . '">' . $post->post_title . '</a></li>';
                        	}
                        	$output .= '</ul>';
				set_transient('msblog_outputs', $output);
                	}
			restore_current_blog();
			return $output;
		} else { return $output; echo $output; }
	}
}