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The swelling could be a cyst, a neurofibroma (localized harmless swelling in a nerve), lipoma (localized collection of fat), a swollen lymph node, an abscess, or folliculitis (hair follicle infection). It is difficult to comment without examination. Please consult a doctor for examination followed by probably a CT scan for confirmation. Take care!
It could be a sinus infection. Do you have the symptoms of runny nose along with the sore throat? Even if you don't have rhinorrhea (runny nose) still could be sinus. Check the lymph node, if the swelling is less than an inch, then you needn't to see the doctor. See the skin colour above the lymph node, if the skin is red or pink, it means that the lymph node is loosing the battle against the infectious agent, you better get yourself checked then. Some drugs( like anti-epilepsy drugs Phenytoin) or vaccine (for typhoid fever) could also cause painful lymph node swelling. If other signs like fever, weight loss , tiredness and weight loss are accompanying painful lymph node, you better rush to the hospital, could be the indication of serious infection,.