I would give him a small dose at first maybe 5-7 drops every half hour to hour. Then tomorrow up the dose 10-12 drops until you are able to give him a full dropper. REMEMBER if it effects him lower the dose he may have to much of it in him.
Yes it won't affect him, I had a buff orpington roo with wire neck at 2 1/2 week old and now he is a happy healthy 3 1/2 month old.
Also do you have natural women's vitamins? in so post a picture of the ingredients
Aww poor baby giving him room temperature egg yolk every few hours with some much(mush being chick feed with hot water cooled down and absorbed) hope your little baby feels better bad start to the glorious chicken world little baby. : (