Pullet cant keep upright... Any advice?

I have one young pullet that ive had for about a month and a half. Last thursday when i came home from work I couldn't find her to lock her into the coop. The next morning i didnt see her but she appeared inside the coop aoon after i opened the door in the morning. At quick glance then she seemed fine. When I came home from work that Friday I notice she was having a hard time getting around and I had to physically put her in the coop to lock her in. By Saturday she was the same so I put her in a dog crate to separate her. I also gave her some electrolytes and probiotic in her water. She couldnt really stand but could hoop around sorta. By monday after work she stopped moving and from what i can tell eating too. Her poop is clear and wet mostly, Then tuesday evening i found she cant even keep herself upright and was sweaty from trying all day. I gave her some nuti-poulrty last night and this morning. And now have her propped up in a towel to keep her upright but dont know if nursing her along is doing any good.
Google points to marek since she cant stand but idk she since she was m.i.a the night before this all started and her eyes look good to me.
Below is a picture from this morning

when they do that,no cure.probably mericks which will spread.sorry to hear this,we get attached.

Her poop looks better and normal. she is better about keeping her in a head up but still pretty much paralyzed, thinking if she makes it to tomorrow I'm in a take her to the vet to see what it is and know if I need to cull or not.
The last couple days I have noticed a sore on her leg that could be a bit wound or bed sore but its located toward the front side. Hoping its not mareks, so far all other hens seem fine even thou they keep checking on her in the dog crate.

Outcome: I just thought i would post what happened at the vet. The vet put her down. She dislocated both legs by a fall most likely and its the best thing to do for her but atleast i now know there wasn't anything i could do and this needed to happen.
On the bright side she doesn't have anything like mareks that is contagious to my others.

Sorry for your loss. She must have had a hard fall or was injured by something.