You might try a chick chair or sling to get her up off her legs and to help keep her clean. Mycoplasma synovitis is a respiratory disease that has few respiratory symptoms, but can infect the joints. Usually there will be swollen joints in the feet, hocks, and can be in one leg or both. There can be yellow drainage around the joint. Antibiotics such as Tylan (tylosin,) chlortetracycline, and others may treat symptoms, but it can be chronic and infect others in the flock. There can be other bacteria or viruses that can infect the joints. I don't know if that is what she has, or if it is an abscess or injury. Here are some pictures of chick slings and chairs:
This is 10 week old "Peanut"....I found him not getting up or walking 2 weeks ago; he's been in his new chair for a week now.
Both hocks are a bit swollen and warm.. Been giving polyvisol w/out iron, probiotics, Apple cider vinegar in water, fresh herbs, Vit B complete, plain yogurt, eggs, veggies and regular feed mix.
I have no idea what caused his paralysis.