Your CDN extension is improperly converting the line below to act as though it's coming from the CDN and not from Facebook's site:
js.src = "http://checkcdn.diystash.com/connect.facebook.net/en_GB/all.js";
Should be:
js.src = "//connect.facebook.net/en_GB/all.js";
That is a bug in the CDN plugin that will need to be fixed or worked around. If you contact the extension developer, please tell them that they should not make "Schemeless links" load from the CDN. Schemeless links are ones that start with two //, and are part of the HTML specification and the way we load the Facebook Javascript library uses them (and it's the way recommended by Facebook itself).
Hope that helps get you started,
Alex