hey guys... There is a lump on the left side on the shaft it isn't there when not erected but when erected it is becomes hard and visible .It has no pain , it's kinda under the skin plz tell me what is it i am only 17 and have gotten really scared ...I remeber once in school my penis was erected and i was punched in the penis real hard i think maybe after that it has appeared please tell i really scred :'(