Swelling pain under the ear may be caused by acute lymphadenitis, acute mumps, ear inflammation, folliculitis and so on. 1. Acute lymphadenitis: Due to low immunity, bacterial or viral infections cause acute lymphadenitis to occur, which may lead to swelling of lymph nodes around the ears, causing swelling and pain under the ears. 2. Acute parotitis: Below the ear is the part of parotid gland, if acute parotitis or acute suppurative parotitis occurs, it may cause redness, swelling and pain below the ear. 3. Inflammation of the ear: If you suffer from boils or otitis externa, it may lead to localized involving pain, which in turn may lead to swelling and pain under the ear. 4. Folliculitis: The hair follicles under the ear are infected by bacteria or germs, resulting in local redness and hard lumps, and the stimulation of inflammation may cause swelling and pain under the ear. If you have pain and swelling under the ear, you should go to the hospital for examination and follow the doctor’s instructions to standardize the treatment.