Fluttershy is shocked when she wakes up one morning by rainbow dash storming into her cottage,,,,without a mouth?

Who could have done this?
If it was Discord then why would he do this, why would he make Rainbows mouth go away?

But when they finally find him things gets more complicated than Fluttershy thought it would become.

Fluttercord (FluttershyXDiscord) with a hint of Flutterdash (FluttershyXRainbowDash)