Why does my S5 keep showing empty threads in my messages app?/continuous vibrating?

[AC Question]

When I open my messages app I can see old unknown numbers(that I used to text LONG ago or even saved names/numbers) pop up with an empty thread, I delete it from the conversations and they still pop up later, either the same number or a different number ..
Also, when I receive a text message and my phone is on vibrate it continues vibrating until I've finished replying. :/ This just started today and i'm ready to throw my phone out the window.