my daughter is 14 months old while walking n running she falls at her back regularly... is this a sign of deficiency of anything

A. At this age kids don’t even walk a comfortable and your child has already trying to run so that’s a very very good milestone that your child is achieving and falling down is a part of running and learning to walk so it’s not a problem but yes I would save the child is getting hurt at the same place every time then it’s a matter of concern