Falling over and poop

I had 3 chickens go to a show. 2 came home just fine. We checked out Saturday night and on Monday my Araucana started having problems (so it will be a week tomorrow that she's been sick). She's about 18 weeks but she hasn't laid yet (just throwing that in in case it could be egg binding on her first egg?? She doesn't really seem like she's trying to push anything but symptoms could possibly fit...maybe?) . Sleeping a lot. She was still eating and drinking on her own until 2 days ago. She could stand but was just stumbling trying walking around. Her poop was very green and was coming out with a lot of liquid. She's been fluffed up and just seems miserable.
I've been giving her nutri-drench, electrolytes, and probiotics. And feeding her egg yolks along with her chick feed. I've been soaking her in epsom salt baths, they don't seem to be helping but she seems to enjoy them so I've continued those.
Someone suggested to me it was sub-clinical coccidiosis and to start her on corid. I did that Friday and now she's not pooping at all, it's just like liquidy whiteish-yellow stuff and she doesn't want to eat and I'm having to dip her beak to get her to drink. She's falling over to her right side and in is even sleeping leaning against the cage to prop her up. She's shaking her head a lot more now too and still just fluffed up all the time.

I've been combing the chicken health handbook and it just sounds like everything and nothing and I just don't have the experience to know what I'm looking for!

SO what does this sound like to you? Would you continue the corid (this just doesn't seem like cocci to me but I don't know). What else can I do to help her? Should I try calcium or does this not sound like egg binding will it hurt her if it's not egg binding? Or if there is nothing to be done what can I do to make her more comfortable or at what point should I just put her down because she's so miserable?
Thank you for any help!

 

Thanks. I don't have a vet nearby that will see chickens but I'll call and see if they will do the tests.
Her crop is emptying.
She was at the show for 3 days- so it doesn't make sense that she would have picked up Marek's there. If she already had it though and is now showing symptoms that means my whole flock has been exposed and I exposed all the chickens at the show, right? That sucks- I'll feel so terrible if that's what it is.