Quote: Very sorry to hear that.
I'm also very sorry I took so long to reply, this site has mucked up and stopped notifying me of replies to threads and has just generally been unreliable. I didn't see that you'd replied until just now. For what it's worth by the sounds of it there's nothing you could have done. A vet probably couldn't have done anything either.
The brownish diarrhea and blackish comb could mean a few things, from possible organ damage, possibly from internal injury, to septicemia, to an illness, or it could be something she ate that perhaps caused poisoning or again organ failure or damage. An extremely bad case of cocci could also be it, and some internal parasites can be amazingly aggressive and harmful, for example barber pole worms in sheep and goats can take a healthy animal to death's door in as little as 24 hours. But from her symptoms I think internal damage is more likely.
The bad-smelling brownish poops, and the blackish comb, could suggest dead blood cells from for example an internal hemorrhage, or organ failure, that's become septic. Organ failure, especially kidneys or liver, or severe damage to some organs, often causes severe and rapid weight loss. Perhaps your rooster was overenthusiastic/clumsy and dealt her a break in her skeleton that perhaps pierced an organ or caused enough trauma for internal infection to set up; severe enough bruising, even if the skin isn't broken, can in some cases do the same thing.
If she could get up off the tiles but chose to be on them that's a good indication of internal infection and/or pain. The heat and swelling caused by the infections often drives direly unwell animals to seek a cold place to try to numb the pain, even if they're unable to stay warm enough to survive there. Animals that are terminal cancer patients often do the same thing.
I would watch the others closely though just in case this is in fact an illness that's struck the weakest first.
Best wishes, sorry for your loss.
