Sorry for your loss(es).
I personally MIGHT want some sort of reimbursement from said breeder for loosing chicks less than a week after purchase.
I agree that coccidiosis could cause nutrient deficit leading to wry neck... and IF you thought you were noticing something.. probably true. In theory your supplement may have been preventing it... can you post a pic of what you were using?
And can you verify if you bar ale non medicated feed is actually a chick starter? No judgement here, just trying to help look for clues to prevent any further death and maybe get you comfortable with whatever chicken adventure you wish to pursue next year.
