I have read to treat with 2 or 3 drops a day of infant vitamin drops, dropped on the side of the beak so that they pull it into their mouth. You should be able to buy them at the drug or feed store. PolyViSol is the old standby brand. Buy the kind without iron.
This is from the sticky on this forum, under medications:
Wry Neck (Crooked Neck)
A bent neck can be a genetic condition or can be the result of a vitamin deficiency. When it is the result of a genetic condition, there is no treatment. Some breeds, such as silkies, are more prone to getting it genetically. Vitamin treatment is still worth a try. If the wry neck is a result of vitamin deficiency, the vitamin treatment should clear it up.
Vitamin E gel caps with Selenium - give the chicken the liquid from the gel caps. Make sure to get the kind with Selenium for proper absorption.
Polyvisol without iron - this is a liquid vitamin supplement labeled for infants. Get it at the drug store or some grocery stores. Can be used in addition to vitamin E when treating wry neck.
A more comprehensive treatment:
First week:
Twice a day
2.5 mg of prednisone
400 IU of vitamin E
Once a day
A piece of human vitamin B complex pill or a squirt of human liquid vitamins
Selenium (50 micrograms/day for half size juvenile for 3 days)
For the second week:
Once a day
2.5 mg of prednisone
400 IU of vitamin E
A piece of human vitamin B complex pill or a squirt of human liquid vitamins
Every other day
Selenium (50 micrograms/day for half size juvenile for 3 days)
For the following weeks:
Once a day
2.5 mg of prednisone
400 IU of vitamin E
A piece of human vitamin B complex pill or a squirt of human liquid vitamins
Every third day
Selenium (50 micrograms/day for half size juvenile for 3 days)
Do not abruptly stop prednisone, the swelling rebounds, decrease dose gradually.
Vitamin E recovery can be slow; continue the vitamin E for several weeks at least.