Sites not showing up or show up after delay

So I finally managed to get multisite subdomain configured properly (or so I thought). I added 2 test sites yesterday, and though I had problems with accessing their dashboards or viewing them via URL, they are running fine today. Encouraged, I added a few more sites today and they appear in the Network Sites list but I can’t access their dashboards and I can’t view the sites, I get “Server not found” error messages in both cases for all of the new sites. After hours of searching for a solution, I am at a loss.

Just thought I’d post my .htaccess, since I’m not sure whether or not this could be the source of the problem or something else. Here goes:

SetEnv PHPRC /home/webs/mysite/public_html/php.ini
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ – [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]

Any help with this would be appreciated.

Thanks!