R.C.
Hi H.. I'm not sure about the gross motor delay, but the fact that your daughter is in the 5% for weight may be an indicator of celiac. As I'm sure you know there are malabsorption issues that go along with it, so a gluten free diet may help her get the nutrients she needs and put on a few pounds. My BIL was recently diagnosed. This is a guy who was skinny as a rail and could not gain weight. The diet made all of the difference. He feels better and looks healthy. Good luck!