My chickens skin is turning black!!!

[dtbdca]

Link is sick again she's eating by herself but it seems as if her eyesight is getting worse because she misses when she pecks at things. She weighs almost nothing and her skin is turning black and goopy. I've treated her for mites and lice even though I couldn't find either. I also treated her for worms but nothing has been working. I've been giving her a lot of Nutri-drench and it seems to help a little. She is getting so weak she won't even stand up. Please help!

 

[dtbdca]

This is her skin

 

[friendofhens]

Did u find solution? My hen is in similar condition