My Plymouth Rock who is around 10-11 months old (it's always the Plymouth Rock) has been a bit under the weather. She is lethargic, she doesn't move around much, she doesn't eat a lot. She just lays down. I have wormed them, and given them some natural yoghurt. I am going to try some garlic in their water to boost their immune systems. She doesn't lay eggs, so is it possible she has weak legs from eating layer mash when she was very little, or has she got some viral infection, or parasite? Our other girls are completely fine, but our Plymouth has been this way for about a month now.