Chicken has less features and swollen patch of skin above butt

[Keytar]

Hello! So my chicken has started looking feathers a few months ago and I never really knew why. Then yesterday I saw her picking at a patch of skin inside of her tail feathers just above her butt. It is red with bits of white, yellow, and even black. I am really worried. I have been separating her from my other chickens so they don’t pick at her, but as she has been separated, I’ve been noticing she has diarrhea. I don’t know what it is but does anyone else know? I hope it is treatable, she is such a sweetheart chicken

 

[Wyorp Rock]

Welcome To BYC

Can you post more photos of her and a further out shot of where this is located on her body?

Inside the tail feathers just above the tail, can you see the preen gland? Is it inflamed or swollen?

The feathers look to be broken and the black bits look to be scabs. Check to see if she's got any lice/mites on her.

 

[Keytar]

Welcome To BYC

Can you post more photos of her and a further out shot of where this is located on her body?

Inside the tail feathers just above the tail, can you see the preen gland? Is it inflamed or swollen?

The feathers look to be broken and the black bits look to be scabs. Check to see if she's got any lice/mites on her.

Here are some more pictures of her! The second one is the feathers she has lost. Now that I check it again it looks like it is really dry. To me it looks like it is swollen.
It doesn’t look like she has any mites or lice on her

 

[Wyorp Rock]

Looks like feather picking.

 

[Keytar]

Looks like feather picking.

Ok thank you! I’ll do some research on that