The certificate Cloudflare provide for you only cover for
*.nutpanda.com. For sub-subdomain, you’ll need to purchase Cloudflare Dedicated SSL with Custom Hostname for $10/month.
Alternatively, if you are in Business or Enterprise plan, you can upload your own custom SSL certificate.
How about creating Page Rules that redirect any www to the non-www? Something like:
https://www.*.nutpanda.com/* redirect to https://$1.nutpanda.com/$2
Have you tried it?
That’s something you would have to try from the Page Rules tab in your Cloudflare account.