Yeah, just give her eggs to meet the selenium need.
I know how toxic selenium can be. At the Calif. state park I retired from and was required to live at in state housing, we were discouraged from drinking the well water which tapped into the water table beside the Colorado River and had such...
Wry neck treatment suggests no more than 25mcg of selenium, but it doesn't indicate what the strength of the Vitamin E is in that supplement you posted. You would probably be safer to just use a straight vitamin E 400iu capsule and shave a sliver off a selenium tablet.
I believe Bibby will...
I agree with your assessment. Everything points to wry neck. If it is, she should respond quickly to vitamin E therapy. You probably know what to do, but if not, it's 400iu of the E and a sliver of selenium.
The only other thing it might be is a crop disorder. It wouldn't hurt to monitor her...