Suggest Cure For Swelling In The Ears

My sons ears swelled up today. Almost the entire ear on both sides except for the earlobes are thick, red, and swollen. He does not like them touched but otherwise is acting rather normally and doesn't seem to be in much discomfort at all. I have given him Benadryl once because I thought it may be an allergic reaction to something he ate or perhaps a bug he was stung by. He is 4 years old, and 40 pounds.