Your grand daughter is having scaly round patches.. More on trunk.
She feels irritation and itching.
She must be having throat pain and mild fever.
With all this history , I feel that she might be having guttate psoriasis
Guttate psoriasis is found in children usually following throat infection
It is a mild condition and usually cured without complication.
In past, many doctors were advising tonsillectomy
as a treatment of guttate psoriasis.
Apply mild steroid with salicylic acid
on lesions at night.
And moisturising cream in morning ..
Antihistaminics and antibiotics may improve the condition.
Do not give oral steroid ..
Still, consult dermatologist
for firm treatment .
I hope you got my answer.
Dr. Ilyas Patel MD