I do not know anything about this, but I wanted to say that I am sorry you are going through this and I will pray for you and your little one, best wishes
My son didn't have small head size necessarily, but at my later u/s various areas measured differently. For example, abdomen might have been ahead, legs behind, etc. etc. He was born small, but perfectly healthy and is now a healthy 8 month old. I don't think this is all that uncommon, but it is good you are getting things checked out. It's impossible not to worry, but in my experience they double check everything just to be safe. Rarely is there a problem picked up at this stage that was missed earlier. Good luck, and please let us know how you are doing.
Can you give us an update? 34 week ultra sound just came in and baby’s head is measuring small.