This is going to sound crazy… but bear with me as I am in the same boat as you and this information was just brought to my attention yesterday.
Has anyone ever looked at head circumference? I am taking my LO to a surgeon this week in hopes to solve his reflux issues, but the surgeon asked about his head circumference. He said that fluid on the brain can produce reflux and reflux like symptoms and interfere with sleep in a wicked way (babies with this cannot sleep or lay down very long as pressure builds up). Worth asking about, right? If the circumference is/was in the 95th percentile, there could be fluid.
Good luck to you… I wish you comfort soon.