Hen died this morning

Hello there. I'm 25 and I live in Newfoundland, Canada, in a suburban area & have been caring for 6 hens since last august, so say 9 months. Friday evening I noticed what looked to be (from reading your helpful forums) a swollen vent [looked like her cloaca was protruding, what I would have described as having her bum inside-out]. She seemed to be in no pain and was happily mingling with the rest, eating bugs and as far as i can tell had been laying regularly up until wednesday or thursday. I used a solution of honey and water to help sooth the area and try and prevent infection. I was out this morning, Sunday, to feed them, all is well, and about 3pm I return to check on them(habit) and the one with the vent-issue had died. I can't figure out what the reason was. Feed them every morning with regular chick feed, and every second day or so I bring in some wild insects. I also try and supply enough oyster shell for calcium. Im worried that this issue might arise, or that the other hens may become depressed (or worse, ill). So worried. If anybody could give me some feedback I will be checking back regularly. I normally get my info from family members who have raised hens, but that generation of men is slowly shrinking. Any feedback or help is greatly appreciated, and I thank you in advance for your condolences.

Thanks a million for the support folks, ill post some pictures when the weather gets a bit nicer, the other 5 are looking fine as ever. Although after the incident I've been trying to pay extra attention to them ;p Good to know its not likely a systematic error or anything likely contagious. New to the game so its always a scare. I was thinking once we got through the first winter everything would be easy-peasy, then a scare like that. Jeez. Anyways thanks again! Love BYC! Not many posts so far but I plan on contributing! ciao!