External ear pain is usually considered to be caused by inflammation and neuralgia in the external ear and surrounding tissues and organs. If the swelling and pain in the external ear is significant, you should generally consider whether there is an injury or inflammation of the auricle, such as trauma to the external ear, eczema, dermatitis, boils, etc.
Metabolic disorders such as gout; immune disorders such as recurrent polychondritis can also cause auricular swelling and pain.