Advice on a lame chicken

So i don't know what happened to her but she hurt herself somehow. When I found her she was limping around and I brought her inside. No obvious deformities. She wasnt really showing discomfort when i touched up and down her legs. The next day she was not mobile and unable to get around much. Since then she has been able to hobble around and stand up on her own. It looks like she's toe walking and isnt very balanced. I have her quarantined away but in the big run with the rest of her flock.

It has been a little over a month now of this issue and at this point I'm not sure if its cruel to just keep her going. She's otherwise alert and active. Eating food, treats, etc. Any thoughts/ insights appreciated.