One of our backyard flock has suddenly (last few hours) got very sick. I'm worried and need advice. I have done research to the best of my ability but can't narrow it down. I'm fairly new with chickens and don't want them to suffer due to my ignorance. She is ~3 years old, Rhode Island Red. She's normally the first to come running for food but midday today she was just sitting inside the coop (up on a perch), wheezing and gurgling. I picked her up to remove her and she was more docile than usual. I brought her out (to inspect and isolate). She sneezed and sprayed me with liquid (Yes, I'm heading to the shower) and she seems to have fluid in her mouth causing the gurgling as she breathes. It sounds like she's breathing through water poor thing! Her eyes and wattle / comb all seem fine but her backside looks like she's also having diarrhea problems. When I put her down on the ground she seemed a bit off-balance at first. Research says it could be anything from microplasmosis to pullorum but she doesn't fit all the listed symptoms and it seems unlikely. All advice gratefully appreciated. (The vet and extension office are now closed in our timezone so I can't find out if there's anything in the area). Many thanks from a concerned chicken-mamma. Background info: The coop has about 30 chickens, 2-3 years old, including 2 roosters, 5 bantams, and a mixture of hen breeds. No new chickens introduced for over a year except a new single healthy hatchling from last week, being reared naturally by a broody mother hen (kept with the rest of chickens). We live in the South East USA (Coastal GA, Bulloch County near Statesboro) in a rural area surrounded by pine trees, wetllands and agricultural crop fields of currently cotton and wheat . The chickens all go to roost indoors at night and range freely in a large sandy area during the day. They have plenty of dust baths and every few days we let them out into the rest of the 1-acre yard but they tend to not go much further than scavenging under the nearby pecan tree. The last 2 weeks have been unusually hot (>90F with heat index >100F) but it cooled back to a more normal 70-85F this last few days. The chickens have a fan in the coop and plenty of shade and fresh water and none seem to have struggled (that's normal summer temperatures here, it just came early). We did have one mature hen drop dead very suddenly in the middle of the day, about 4 months ago, with no explanation. She otherwise had seemed healthy. All other birds seem happy and healthy.