Just to be on the safe side, #3 daughter's neck is going to be CAT scanned tomorrow morning. Happily, the procedure can be done here in town, at St. Michael's Hospital. The idea is to find out exactly where those two dubious vertebrae are.
#3 daughter's not a happy camper right now. I can't say that I blame her. Even though it's unlikely that there's anything badly out of order, knowing that something could be wrong with you neck isn't reassuring.
I certainly hope her neck checks out.