Slow growth in ultrasound ?

Im 26 weeks and 3 days. Today I went in for an ultrasound today and got a call from my doctor. My baby’s humerus went from the 20th percentile to the 5th. They are sending me to a specialist in two weeks for a follow up ultrasound to make sure it was just the angle the picture was taken, and not a slow growth issue.

I tested less than 1% chance for Down syndrome so that should rule that out. But of course as a first time mother I’m getting very anxious.

Has anyone ever had this same issue? (For lack of a better word). How did everything turn out?