baby's head in 10th percentile?

Jaime
So today I had a scan at 36 weeks. He weighs an estimated 5lbs 6oz. They said he's measuring about a week and a half behind and my stomach is measuring only 32 weeks but most importantly his head is in the 10th percentile. I've never had an abnormal scan before and the last one was at 28 weeks. 
They're sending me to a specialist in a week but has anyone experienced this before??