Thank you for your query.
There seems to be no reason to panic. I wish i could see the lesion but by your descriptions it seems to be some kind of allergy
or insect bite.Kindly apply a calamine
ointment and give her some mild antiallergic drops.I hope this will take care of the problem.As a wonderful mother keep a close watch on her.It she worsens get a paediatric consultantionHope this answers your query.Have a nice day.