Separate her immediately. Put her in a small cage or box, preferably inside where she can be observed and treated. I don't know about the orangy stool, but it could be coccidia. That would be treated with sulmet in her water...can purchase at local feed store.
The mucous is some sort of upper respiratory infection probably. The sulmet can also treat infectious coryza, if that is what is causing the mucus.
Coccidiosis is a disease caused by microscopic protozoans (one-celled organisms) called Coccidia that affect fowl worldwide. It is generally found in the terminal ileum, caecum, and rectum of chickens. Mortality and morbidity is variable with this disease. Although there are many species of coccidia that can infect fowl, domestic animals, and humans each species is host specific. After an outbreak of a specific species of coccidia, the flock will develop a resistance to the exposed coccidia species but remain resistant to other infective species. Chickens are susceptible to any of nine coccidia species, turkeys are susceptible to seven species, and quail to four.
Signs
Droopy feathers
Poor production
Ruffled feathers
Closed eyes
Diarrhea
Pale face
Paralysis
Blood in feces
Infectious Coryza
Infectious Coryza is caused by the haemophilus paragallinarum bacteria, and is very common worldwide in fowl.
Signs
Watery eyes
Facial swelling, including one or both eyes swelled shut
Foul smelling discharge from the nose
Diarrhea
Low egg production
Wheezing
Here is a link that may be helpful in identifying what it may be. You are the best person to be able to determine the exact symptoms. Good luck!
http://ultimatefowl.atwiki.com/page/Poultry Disease