It could be organ failure. Honestly I think you're doing all you can at this point. The only thing you can really do is try and keep her comfortable...
Protein depends on the brand. One of my local brands of layer is a 17% while their grower is a 16%. Check your bag analysis and make sure. You could start transitioning to a layer feed or like I said, just leave a calcium supplement out.
Grower feed doesn't have enough calcium on its own to support egg production. Make sure you have a container of crushed oyster shell or calcium carbonate grit on hand that they can free choice select from.
Respectfully, the word "antibiotic" means "against life/life-destroying" and is not specifically targeted to just bacteria, which is why amoxicillin is not labeled as antibacterial.
Whiskey and other alcohols are excellent for topical disinfecting, however applied internally it will affect your...
If she's getting selenium, vitamin E, and B vitamins I don't know what else there is that you could try to be honest. 7 is pretty old for a healthy chicken, let alone a chicken with inbreeding and other genetic issues.
Amoxicillin and other antibiotics have been around a long time and are now overused, causing a drop in their effects. Research to new antibiotics is a slow process, and there are in fact certain strains of antibiotics that are heavily restricted because they are the ONLY things known to fight...
If she took x-rays then it's not likely broken or dislocated but it could be sprained potentially... he could have also had a nasty shock losing the fight and lost confidence.
How many roosters and how many hens do you have?
This is going to be a slightly silly question, but have your birds been getting berries or other dark/reddish foods?
Have you introduced any new birds, had any stressors like moving or a predator scare?
It doesn't hurt to dose the flock with Corid or another amprolium product just in case...
You'd want a 0.5% permethrin then.
Take a look at this article.
https://www.backyardchickens.com/threads/treating-sticktight-fleas-echidnophaga-gallinacea-on-a-duck.1283862/