1 chicken dead, 1 sick = symptoms is bloody swollen prolapsed vent

[Debz1202]

6month old Isa Brown female. 1st chicken was lethargic, eyes closed, mucus on beak and bloody prolapsed rear. It was as though it kept pushing because the hood/vent would expel more and have bubbles with the "straining". This chicken was kept comfortable and separate from the others while it was breathing, until she passed. When I went out to examine the other five I found the bloody rear of another female. So I brought her in and separated her because the others were pecking at her while was examining the coop. Prepared Electrolyte water, along with Apple Cider Vinegar and crushed garlic. This was offered in her cat crate where I kept her and she looks improved this morning without active bleeding, still protruded somewhat. I sanitized the coop, removed old bedding and shavings and put down new. Prepared the same concoction of fluid for the other 4. No store sells the antibiotics any more to add to the water. What most likely is this and how can I help her while not losing my whole flock? Thanks in advance.

 

[Debz1202]

Of note, I did perform an exam of the vent and there is no egg stuck, etc.