My chicken is dying

[Iamahz57]

I have Golden Comets and one is between 4 to 5 years old. She has had good and bad days for around 6 months and I think she actually laid an egg about a month ago.... 3 days ago she made a point of being by herself and started going downhill after that. This morning I noticed her head feathers were turning black even tho her comb is still red. What does this mean? Feeling bad about my Sally girl.

 

[casportpony]

Can you post a picture of her?

 

[artsyrobin]

Symptoms will help, poop pics, hows the crop? any white vent drainage? Had a recent fecal, check for mites?