Sometimes it is difficult to figure out what they have wrong with them. So all you can do is go by the obvious symptoms. Since she seemed to have crop problems, check her crop. If there is a hard lump in it, it is may be impacted. Only on impacted crops do you want to use olive oil. The oil helps break down indegestable foods in the crop and intestines. It is other wise very difficult to digest and should not be used if the crop is sour. You mentioned she was pooping, so things seem to be moving so I doubt impacted crop.
If the crop is squishy and full of gas or the like, than it is a sour crop. You don't want all that gunk staying in her crop too long, so you can hold her like a football in one arm. Support her well as you lean her forward, (never backward) and while leaning her forward you massage the crop so she will "vomit" the gunk out. Hold her like this for no more than 10 seconds at a time so she can breathe. If anything comes out, you can try again. You will never get it all out, but anything helps.
If you think she does have a soured crop, you need to get her on raw unfiltered apple cider vinegar. 3 tablespoons in a gallon of water. If she is not drinking, you can squirt this down her throat with a syringe. She will need hydrating and the ACV will aid in killing off the yeast/fungal infection in her crop.
Make sure she is not egg bound. When was the last time she layed? Feel around her vent and abdomen for an egg, although you said she was pooping, so chances are she is not egg bound close to the vent. Feel up her abdomen near to her legs and see if you can feel an egg somewhere.
Stick to easy to digest foods, like the yogurt. Try hard boiled eggs, cereal, cooked rice, even crackers. Anything to get her to eat. I have found that sometimes you need to feed them what ever they will eat just to keep them alive.
Does she have ANY symptoms of respiratory illness? Runny nose, coughing, sneezing, etc.. Check her for mites. Look around the vent and the front and back of the neck. The skin may have welts or red bumps on it. Bugs can suck the life out of a bird to the point of death.
Has she been wormed recently? Worms will also drain the life out of them to the point of death.
She could have an internal infection, or other internal issues. If you suspect anything, you could start her on antibiotics. Feel over her entire body for anything suspicious.
And the most important thing you can do is keep her warm. A cold bird loses calories and makes them sicker. So keep her indoors or under a heat lamp outside at night, even during the day.
Right now I am dealing with a girl that has been off her feed and water for almost one week. I have been coaxing food down her throat for days and she has been under a heat lamp for the past 5 days. Just yesterday I started her on antibiotics as other than her having no interest in food or water, she has no symptoms. So I am thinking internal infection. She was not drinking as of yesterday so I was squirting antibiotic water down her throat every 3 hours. Today I did see her drink on her own.
So if you are unable to figure out what she has, do your best to keep her comfortable and warm. Get her to eat anything she will eat, but try to keep it easy to digest. You may have to force water down her throat. Do all you can until what ever she has passes. If all else fails, you can try antibiotics. Make sure to use plenty of yogurt or probios after antibiotics if you use them.
Keep us posted and good luck! I am right there with you on this one with my girl.
