My first thought, looking at the page count, was: too long. Opening it, though, I was impressed. The writing is engaging. Still, I have to ask -- how does one exhale in sloppy exhaustion? What does that mean? I'm not sure.
I see, the man "coughs up a mouthful of blood." Knowing this, you might want to rewrite the above line. Rather than describing his cough as sloppy (a vague discriptive), you might describe it as wet, broken by gasps. Whatever the case, the line threw me. It's weak.
You go on to write: "A large and cavernous space..." A space that's cavernous is, by definition, large. That said, the line is redundant.
The writing is, I think, a cut above. still, it's not, if you examine it, good. It is, though, interesting.
Doubt I could do better. It's much easier to critique than to write. That said, I'll continue to read and comment -- if you're around. By that I mean, if you show an interest in the opinions of others.