Rhode Island Red can't walk and is breathing through mouth

[Ems]

3 days ago my 4 month old rhode island red stopped walking. She was fine earlier in the day, but when I walked out outside later on, I noticed her laying down on her side and unable to get up. I thought she was injured at first, but I checked her all over and didn't see or feel anything out of ordinary. She is able to kick her legs and move her wings, but can't seem to bear weight on them. She can move her head around and is still eating and drinking. Recently she has started to breathe through her mouth. Any ideas on what it could be? I'm thinking its mareks, but I'm not sure. I have one other chicken, the same age as her and she is totally fine. I bought some Durvet vitamins and electrolytes to put in her water, but I'm not sure it will even help.

 

[DaisyBuff]

Ether she is super hot ( doubtful ) or she has a lung problem.

 

[Eggcessive]

I would have to agree that Mareks could be a possibility with her age and symptoms. Hopefully not. Was she vaccinated for Mareks? Can you bring her in and give her water to drink in case she is dehydrated? Is she cold? Electrolytes, pedialyte, gatorade are food as well. Do you have any pictures of how she is lying? Can you check for egg binding by inserting a clean finger inside her vent anout 1-2 inches?

 

[Eggcessive]

Here are some good articles to read about Mareks disease and other conditions that might look similar:
http://csu-cvmbs.colostate.edu/Documents/vdl-mareks-disease-fact-sheet.pdf

https://www.backyardchickens.com/articles/the-great-big-giant-mareks-disease-faq.66077/