Luv2: There is no right or wrong answer with vacines and medicated food-its all personal chocie/expereince. I am thinking this was just a weak chick and possibly something internally wrong. Good luck!
Susan-first I am so sorry you lost a chick!
I would watch and see if any others show signs of illness. If not, I would suspect there may have just been something wrong with this lil one.
What are you feeding them? (Just curious if medicated or non medicated)