Hi there Pokey
Welcome to SC

I think Julie has cracked that right on the head, lichen striatus seems the most logical choice.
Check for damage to nails such as pitting or deformations, that's a frequent give-away.
I hope the appointment goes well for your grand daughter. lichen striatus often effects young children. Hopefully things will get sorted for your little mite then.
At least if it does turn out to be LS then the good news would be that the symptoms should subside within a year or so. Not much sollice for a young child thoughm a year is a long time for children.
Please keep us posted of how things go.
Thinking of you and your grand child
