How old is Ava? Is she a refluxy baby?
Clara did that all the time and I thought it was just something babies did
but after she was given medication for reflux it stopped. Later I was reading the Crying Over Spilt Milk
site and I noticed it said that "some babies may hold their head to one side in an unusual position to ease their discomfort"
But obviously if she is not refluxy it's not the cause, I just thought I'd throw it out there...