From the symptoms it definitely sounds like hives
(medically known as urticaria) are red, itchy, raised areas of skin that appear in varying shapes and sizes. They have a tendency to change size rapidly and to move around, disappearing in one place and reappearing in other places, often in a matter of hours.
Many cases of hives
are "idiopathic," meaning no cause
is known. Others may be triggered by viral infections or medications.