Q: Can no longer sign in with my Apple ID (non-apple email address based)

Hoping someone out there has a suggestion on how to fix... As of this morning, upon attempting to load a new app into my iPad 3, I was told that the Apple Store was not available. This prompted me to update to 8.2, along with upgrading iTunes to 12.1.0.50

Long story short, I can no longer sign into my Apple ID anywhere, except in iCloud, including:

• iOS (iPhone 5 / iPad 3: Settings, Apple ID) - "Cannot connect to iTunes Store"
• My Apple ID site (https://appleid.apple.com/account/home) - "An unknown error has occurred."
• iTunes - "We could not complete your iTunes Store request. The iTunes Store is temporarily unavailable. Please try again later.
• AppStore (in OS X) - No error, login simply cycles

Anyone else experiencing this? I'm a Canadian store user, with an 8+ year old Apple ID.

Thanks!