It's possible that the term existed before Hillary/Trump but your examples aren't it. In your examples the word "fake" is used as an adjective to the noun "new

It's possible that the term existed before Hillary/Trump but your examples aren't it. In your examples the word "fake" is used as an adjective to the noun "news site". As in "a fake news site". "fake news" as it used today is a noun in its own right. As in "that's fake news" See also "alternative facts".