The swelling of the root behind the ear is often due to inflammation, sometimes due to an infection in the ear canal that involves the lymph nodes behind the ear, and sometimes the lymph nodes under the ear are also involved, so the swelling is obvious all around. It is also possible that there is a powder tumor growing behind the ear, which is usually seen in young people. Repeatedly touching it with the hand is particularly likely to cause the powder tumor to become infected, so swelling may also appear behind the ear. If there is inflammation in the ear, you can use levofloxacin ear drops to reduce the inflammation. However, if there is a powder tumor behind the ear, it will eventually require surgery to solve the problem, so it is recommended to actively deal with it, and the symptoms will definitely improve afterwards.