hi..thanks for your query
You may be having localized urticaria
complicated secondarily due to itching.This is an idiopathic condition in most cases.I would advise you to notice if any food,smell or any other external allergens are causing it.Do not scratch the lesion at all.You can have oral anti allergic medicine like Allegra
to reduce it.
If you are having the symptoms since long , you ca undergo a Patch testing to confirm the allergens and avoid the same.In creation cases a bloodwork might be required to rule out internal causes .
Hope this is helpful.Take care!