What type of bird is affected? First, be very careful with your dosage of selenium. While an essential nutrient selenium is also highly toxic when overdosed.
You might try the baby vitamin 'polyvisol without iron'.
I suspected a brain injury in the bird I treated for it- it was a young pullet (silkie) with a large vault that was in with others her own age. The week a few of the young cockerels finally displayed their sex and started acting like rowdy young boys, she started having symptoms of wry neck. I suspected a peck or hard bump to her head affecting the brain and treated it as such (I had access to some anti-inflammatory steroids and did a taper as well as vitamin supplementation).
It worked for me, although the cure was not instantaneous or complete. She continued to show signs for months when stressed/handled. Now she is doing fine, and has not shown symptoms when stressed recently.
Good luck.
