I wouldn’t consume a sick animal. Most diseases in poultry can’t affect humans through their meat or eggs, but it could be a mixture of several severe bacterial diseases or parasites causing the diarrhea.
If you’ve have possible MG in the past, that’s likely the culprit of your bird’s illness. MG is a lifetime chronic respiratory disease that’ll never go away and your birds will shed it through their feces, feathers, dander, respiratory secretions, and other bodily fluids (such as blood or saliva).
I agree with it being Scaley Leg Mites. If he’s been around the rest of the flock, you may need to watch everyone else to make sure it hasn’t spread. I would also recommend cleaning out the coop thoroughly and spray it down with an insecticide that’s safe for chickens.
Depending on which disease is causing their symptoms, most respiratory infections in poultry aren’t curable, but are treatable with antibiotics for when symptoms show up.
It sounds like it could be Mycoplasma Gallisepticum (MG) or Infectious Coryza as those are the most common respiratory...
Have you checked inside her mouth for any lesions or blockages? I think I agree with @Eggcessive about your bird being exposed to Mycoplasma Gallisepticum (MG) or another respiratory disease such as Infectious Coryza. What type of bedding are you using currently?
It almost looks like she got injured or something there. It’s still possible for it to be something respiratory related, but the swelling is in an odd shape. Could she have been bitten by a snake or some sort of bug by chance?
Looks normal to me.. maybe it’s the lighting? Ocular Marek’s Disease is a slow and progressive ocular disease, causing tumors to grow and destroy their eye sight. It’s not fatal.
Her poop looks normal to me. Looks like a cecal poop. As for her backend, could another flock member be picking on her? Other causes of this can be molting or Ascities Syndrome.
Sounds like she may have something inside her nose causing the noise. Or her respiratory tract is irritated by something and it’s causing the squeaky noise you’re hearing from inflammation.