Painful swelling behind the ear is usually seen in two diseases: First, swollen lymph nodes behind the ear. Swollen lymph nodes behind the ear are commonly seen in acute otitis media and acute tonsillitis, and when the inflammation is severe, inflammation of the lymphatic vessels occurs, which leads to swollen lymph nodes in the relevant areas. It usually occurs in the lymph nodes behind the ear, under the jaw, under the chin, and in the neck. Patients can be clearly diagnosed by checking local ultrasound at the hospital. If the lymph nodes are swollen, the patient needs symptomatic anti-inflammatory treatment, and can take oral cefixime, amoxicillin, and penicillin V potassium tablets for treatment, which can gradually heal in about a week. Second, the swelling and pain behind the ear caused by acute mastoiditis, the patient will usually have pus flowing from the external ear canal, ear pain, hearing loss, tinnitus and other related symptoms, and the diagnosis can be clearly made by checking the mastoid CT at the hospital. If it is mastoiditis, the patient needs symptomatic anti-inflammatory treatment, and it is best to be able to infuse fluids to treat it. Cefotaxime sodium and ceftriaxone sodium can be input, and if necessary, surgical treatment is also needed to cure it completely.