I am not sure that whatever is going on with her is herpes-related: Her eyes are clear, no pus, no mucous, no coughing or wheezing, no lameness. She seems fine in every other way except that she's got that nasty green discharge and she's lost weight. And now the lack of interest in food, other than the coveted meal worms and hulled sunflower seeds.
The poo buildup was probably because she has a really fluffy butt so I didn't notice until it it had really built up and caked on.
Your poor hen - that must have been a slow painful death for her. I can understand why you are worried about your survivors. I would be too. I wish chickens didn't mask their illnesses until it's too late to be able to help them (or almost too late).
You bring up something that I was wondering about too - a possible yeast infection. I was thinking of applying some anti-fungal cream (like clotrimazole) to her vent. What are your thoughts on that?
I don't ever give my hens ACV, but I do feed them fermented grains, which is supposed to help gut flora. Funny that she's been off it the last two days though. Maybe it's irritating her gut. Unfortunately I'm not at home during the day to monitor whether she is still eating the layer mash, but will be watching her carefully this weekend. I have given my girls yogurt in the past, but found it gave them all loose stool, so no longer do that. I am planning on buying some probiotics today and will try adding it to their layer mash.
Pet quality wheaten/blue wheaten ameraucanas, welsummers, barred rocks, light brown leghorns; Projects on the go: rhodebars, welbars
You could do a sniff test if you're not too grossed out by the thought.