A Sick Silkie Chick

Head Trauma

First, I'd make good and sure that he's drinking.  I'd use honey and also electrolytes in his water.  Pedialyte will work, gatorade will work in a pinch, or poultry electrolytes . Whatever you can get immediately I would use.  Mixing with a little honey will build up his energy again and tempt him to continue drinking so he gets the electrolytes back in balance.  I'd give that for no less than four days.

Second, continue the polyvisol at a rate of 3-4 drops daily for a week.  If you're concerned about neurological issues, giving 1 capsule of vitamin E (400 to 700 IU per capsule) would certainly work in concert with the polyvisol.  (Of course, slit the capsule and squeeze the contents into the mouth or onto a piece of bread if he'll eat the whole thing).  Do no less than a week.

I'd make sure all of his food and treats are purposeful - nutritionally balanced, and immune boosting.  Boiled egg, some plain yogurt, but mostly a base of a really good crumble or pellet that he will eat that is completely nutritionally fortified and balanced.  If he won't eat well, moisten it or make a mash with the yogurt, etc.  Adding honey to the water with which you make the mash, I find, really helps them to be interested in it.

I'd clear his nares - make sure that he can breathe well.  Honestly after shipping, I like VetRx in the nares and in the roof of the mouth of all birds to help reduce any inflammation they got from the trip in their respiratory tract - allow them to breathe better and decrease chances of any infections setting up in there.

I'd give all the others vitamins and probiotics (yogurt or otherwise), too - to build their immunity for their month of quarantine.

Please let us know how your boy is doing, particularly after a good dose of electrolytes.  I was also going to suggest clearing his vision with scissors but you're on it.    Do watch the shape of his iris carefully.  Gold flecks aren't a  big deal really - but greying of the area, or misshapen irises get into a different territory.  VERY good call checking their responsiveness.  I assume they respond the same on both sides?  Both irises are the same size?