Is this Vitamin E-Oil safe for my birds?

Hi, I was wondering if anyone knew if this vitamin e-oil product would be safe for me to give to my birds?

http://www.drugstore.com/natures-bounty-natural-vitamin-e-oil-30000-iu/qxp16981

The reason I'm asking is because I have a cockerel (8-9 months old) who lost a lot of weight, but is doing okay now in separation. He shakes his head a lot though and appears to have trouble seeing, he also scrunches up his neck and looks up at the sky sometimes. To me it seems as though he almost has wry neck symptoms. We had one chick last year that hit her head and got wry neck. We treated her with vitamin E soft gels w/Selenium (cut the top off and used a syringe to get the oil out and in the birds mouth) and Poly-vi-sol once a day for about a week and she recovered fully. The soft gels though are very messy and hard to work with, and he's a Silkie so I don't think he would be able to swallow the soft gell whole. With this liquid stuff I should be able to just put it on his food, in his water, or straight down the beak and it should be much easier.

We are not sure though, if it is safe, if it will even be effective because it is dl-alpha Tocopheryl Acetate, which if I understand correctly means it's not as easily absorbed and means we'll probably need to use twice as much. Maybe it would just be better to use the soft gels?

Here is the link to the soft gels we've used before: http://www.shaklee.com/products.php?sku=20112

I was wondering if it could be a vitamin D deficiency since we've had to keep him and his buddies cooped up most of the time due to not having completed their run(They are in a new coop). I will start giving him Poly-vi-sol tonight. Supposing it is a vitamin D deficiency, how long do you think it'll be before he starts recovering? (Gaining weight, stopping the head shaking, regains his balance more, etc) It has also been so rainy and hot here that even putting him out in a cage in the yard for some sun has been difficult

Thank you so much!