Swollen and black foot, not bumble foot

My neighborhood chicken is in rough shape. About two weeks ago one of her feet started to swell massively. Now it's black and gross and she won't walk on it unless she really has to. She doesn't have an owner and she's pretty old. I've done some googling and I don't think it's bumble foot. Has anyone seen this before? Any ideas how to help her out? She seems miserable

 

I've been here for seven years and I think she's been here much longer. It sounds bad but I can't bring it to a vet, I could never afford it.

 

Seems pretty normal. It got bad quickly so she definitely walking less. Today she's been in the same spot mostly. Still eating and drinking fine. Although I think she's gonna have trouble finding food and water if she can't walk much. But I can make sure she gets it. I was just hoping there was something to help. She's gonna die soon but I wish she didn't have to do it so painfully.

 

I haven't. Would knowing that help?

 

She doesn't ever get picked up, I don't know if I should bother stressing her out... Is there anything I can do for the pain?