I dealt with this as a chicken newbie within the first year of raising chickens (still consider myself one)... Make her a chicken hammock (there are threads & pictures on here for ideas)... She will progressively get worse as mine did, by day 3 she couldn't even move (must have been in too much pain). I wrapped her leg & toes individually since she kept curling her foot. Taped a triangle shape sponge under her foot. Spoiled her rotten with treats (she lost her appetite). Also took her out of the hammock a few times a day to scratch her neck, back & under wings. When she gained more strength I took her out for "physical therapy" as time went on the sessions got longer & longer. It took 2 full months to recover & another month to introduce her back to the flock.
When you make the hammock be sure she is secure & can't fall out to prevent further injury. Make sure she won't drown in water. Use your chick waterer if you have one still. I think that's it. If I remember anything else I'll let you know.
Give her probiotics & vitamins. I also trimmed her butt feathers to keep her clean... It took a long time to grow back.