Success!
Thanks to some close listening and a bit of Google work (essay avoidance technique #124), I have figured out my mystery song. It's not called "Fallen" after all, nor is it from an album called
Fallen, nor is it by Flogging Molly, so I really had nothing to work with in those departments. Instead, it's a song called "Collapse" from an album called
Wiretap Scars by a band called Sparta. Woo! Now I'm off to investigate their other songs ... I mean, continue work on my essay due tomorrow. Right. Mutter, mutter.