Calling all seasoned backyard chickeners?

Hello!
I wanted to get an experienced point of view on my dilema.
I have a rhode island red that is currently under the weather.
We noticed last wednesday that she wasnt walking around much and standing quite penguin like.
I quarantined her... gave her diluted acv olive oil, checked if she was egg bound and she wasnt.
We gave her a bath because her bum was quite messy.
The next day she still wasnt doing well. I gave her some tylan left over from the last chicken dilema.
Still wasnt doing very well.
She wasnt eating much so i gave her oats and yogurt mashed up wth layer feed.
All the while she was doing nothing but whiteish yellowish diarrhea. We also noticed that her belly on the bottom was swollen and mushy.
She didnt seem like she had a temperature or anything but she also began wheezing.
I brought her to the vet.
They said shes probably not going to make it and did an exam and said they didnt feel any tumors but her insides were mushy...
The vet checked some of the other chickens poo and they had round worms so we dewormed everyone.
While she was deworming she did a bunch of dark green droppings of normalish consistency.
I thought maybe it was worms!
The next day her comb was dull and she wouldnt really stand up. I put her back on the antibiotics.
Her comb has brightened up but she cannot stand.
Still wheezing a little bit at times, eating very little mostly she'll just eat the oats. But is still has diarrhea so I've
been giving her water/ antibiotics in a straw. And watered down yogurt as her poo is mostly water now. If she does stand she just flops back down.
The vet said they could put her down but you never know if they can bounce back so i just brought her home and everyday i bring her outside in her crate for a few minutes hoping she will just spring back up.
Does anyone know what the heck this is or has had anything similar happen?

Bump

Sorry about your hen. My guess is that she is laying internally, or has egg yolk peritonitis. They can have runny droppings occasionally with pale yellow material that looks like cooked egg. E.coli infection, common in EYP, can cause bright yellow droppings. Walking upright or like a penguin is sometimes common. Antibiotics may help prolong life, but something stronger like enrofloxacin might be better than Tylan. These hens commonly can have bloated bellies, sometimes with fluid (ascites,) which can make it hard to breathe. Here are some articles to read:
http://scoopfromthecoop.nutrenaworld.com/tag/laying-issues/
http://www.chickenvet.co.uk/health-and-common-diseases/egg-laying-issues/index.aspx
http://www.theveterinaryexpert.com/backyard-poultry/egg-yolk-peritonitis/
https://www.backyardchickens.com/t/853726/ascites-in-desperate-need-of-some-help-and-guidance
https://www.backyardchickens.com/t/959119/baytril-enrofloxacin-sources

I have had this a couple of times but after a while they have perked up but some have unfortunately died I hope she gets well soon ! Ps we never found out what it is but would love to know

Thank you for our responses. I would definitely want to know what this is incase there is anyway of preventing it. I feel so bad for her she is in such rough shape. I read the article on eyp you left and I think maybe that might be it but I don't know if I could get the baytril or enroflaxin? here?

In the very last link in my post #3, there is info on where to get baytril.