Sick Hens - poopy butts, barely eating, droopy

[Holliewood]

I have 2 hens left, both 2 years old, one red sex link, one gold. The gold, Sweetie has had a wet/poopy bottom for months, had her at the vet, they were treated for parasites, it didn't help much. Have tried pro-biotics, and other treatments and have just concluded that she has "issues". She has always been the runt, but always had the most personality. My red, Gen, who went through an early moult, started in January, seemed to be doing just fine, then about a week ago she started getting poopy butt, however she was still perky and eating, friendly, etc. Now she will hardly eat, just kinds mopes around the yard. I checked both of them for mites, can't find a thing. Their behinds smell bad, are wet with poop and yellow gunk and their skin is red and irritated under the vent. The vet doesn't even know what to think. I am becoming terribly worried about Gen, Sweetie just keeping pushing along as usual with her wet/pasty behind. Gen's crop has been mostly empty for days, she only seems interested in whatever treats I may have. Just today I noticed Sweetie's crop was not very full either.

They are on layer crumbles, Homestead brand, they do get some scratch, although they usually pick through it and fresh water every day. I scoop droppings from their bedding inside the coop every morning and do a complete litter change once a month or so, it is quite clean. They have a 4x8 run to access the outside while we are at work, but free range evenings and weekends. The run seems damp (we live in Michigan and have been getting lots of rain and snow) so I have not been putting their usual scoop to scratch at in it but rather their feed dish.

Any advice from those of you who have been through something like this would be greatly appreciated.

Thank you.