Pain behind an ear can be due to mastoiditis or an enlarged lymph node, according to FamilyDoctor.org. Mastoiditis occurs when the mastoid bone, which is located behind the ear, becomes infected with bacteria, notes WebMD. A swollen lymph node may result from an ear infection or other infection, states MedlinePlus.
One of the most common causes of mastoiditis is an unresolved infection of the middle ear, explains WebMD. Mastoiditis may also result from a skin cyst that develops in the middle ear and prevents normal drainage. The condition may be either acute or chronic. In the case of acute mastoiditis, it's important to seek prompt medical attention because severe health problems may result if the infection spreads beyond the mastoid bone. Patients who suffer from chronic mastoiditis experience persistent ear drainage as a result of an ongoing infection. Aside from pain behind the ear, other symptoms of mastoiditis include fever, a swollen ear lobe, lethargy, redness behind the ear and bulging of the ear.
The pain from a swollen lymph node often subsides within a few days without treatment, but medical attention is important if the pain and swelling is accompanied by fever, redness, unexplained weight loss or night sweats, states MedlinePlus. A swollen lymph node behind the ear may be detectable by feeling the area with fingers. Although the pain often goes away within a short period of time, the swelling may not go down completely for several weeks.