I'm still looking...it's a specific thread on here about medicated feed and wry neck.
I am going to find it! Just give me a little bit.
I'm digging.
For now read this:
"A vitamin deficiency, Vitamin E specifically, can also cause wry neck. If you see evidence of the condition, regardless of the cause, you should immediately step up the Vitamin E in your flock's diet. a well-rounded diet is the key to good health. Treatment can take weeks or longer, immediate results should not be expected, but the sooner you begin treating, the better chances for success.
Also feeding your chicks medicated feed can interfere with their thiamine (Vitamin B1) absorption. Adding some Brewer's Yeast, bran, sunflower seeds or wheat germ to their diet can help build up their B1 supply."
http://www.fresheggsdaily.com/2014/04/preventing-and-treating-wry-neck-in.html