Thanks for posting your query. I feel it is difficult to sort out the problem from your description. How ever I could think of certain possibilities. The first of which could be an urticaria
. The reason being, it is the second episode and last time it vanished without any sequele. This could be due to allergy
which again could be induced by so many substances like heat, cold
, water, pressure, stress
, infections, infestations, inhalations, ingestion, injections, instillations drugs etc. I suggest that you consult the same doctor for a better diagnosis and treatment. If you want further opinion I need all the old investigation reports and the present photograph of the lesion.