head shaking and loss of balance

Hi everyone, I did some searching on the forum, but I can't seem to find any posts of these two symptoms together...

I got a set of 4 hens together that are supposedly all one year old. I say supposedly because only the Americaunas were laying and now only one Americauna is laying and that's irregularly. But that is a whole other post...

My main concern is with the red sex-link who, since I got them all, had been shaking her head a lot, as if to take off a tickling fly. She has never scratched at her head, though. None of the others did this. I assumed mites. I treated with food-grade DE. The head shaking has stopped. Today she is having trouble tripping over things, losing her balance, etc. She also tends to sleep on the floor inside the chicken house rather than on the roost with the others. She does still get out of the coop and go run around and eat bugs with the other girls, just very unsteady.

There is no discharge of any kind, and she doesn't seem to be running a fever. Her feathers are beautiful and shiny, her eyes bright. She is voracious for bread (my bribe). She still is not scratching at her head, but that could just be because she does not want to fall on her face.

I did some reading on Mereks which seems to be a highly contagious disease, but none of my other girls are behaving this way and I have had them all for several months now, so I'm thinking if it were Mereks they'd have all been showing symptoms by now.

Is it possible that it is mites and that treating her with the DE drove them further into her ear(s)? Or is it something else entirely?

One more question - as she is not and has not been laying (possibly because of this problem), I have already given consideration to making her into a meal. I do want to give her a chance. And I'm also wondering if it would be inadvisable to consume the bird with these symptoms (I'm pretty sure she is healthier than the store bought chicken, though).

Any help would be appreciated! Thanks so much!

 

Thank you all for your advice. I still don't know what the bird had, but she passed on after a decline in health. I had quarantined her, tried some antibiotics in her water. I perhaps prolonged her life a few days but I think she had given up a bit sooner than I had. I'm hesitant to get more birds. Does anyone have advice on how long to wait for the other birds to show symptoms if it was something contagious? This seems to have been going on since I got them, and the others are still healthy...
Thanks again!