A sick chick

I have a sick chicken. She keeps tucking her head up under her body and running around backward, which is a pretty pathetic thing to see. Apparently she may be suffering from wry neck, which is a vitamin deficiency; it means I have to feed her children's vitamins with an eyedropper twice a day. I just started this routine today, so I'm hoping there will be some improvement. (I got this information from the Portland Backyard Chickens board, of which I am a member). I called a vet to see if they could help me out over the phone, but of course they said there could be many causes of this problem and I should bring her in for a $45 exam. This brings me to the ethical/moral dilemma of how much I want to spend on a $1.89 chicken. I mean, she IS a pet, but she's also... a chicken, and a very young one who I haven't really bonded with yet. While I was pondering this with my coworkers today I realized that I was standing there eating chicken biryani without a second thought. Are some chickens worth more than others? How would a farmer deal with this situation? (It probably depends on the type of farmer, but I suspect most of them would cull out a sick chicken in their flock). Since my flock is only three chickens, does this mean I'm more responsible for each one? Who knows. Cluck, cluck, cluck.