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Neck lymph nodes can be the result of tonsillitis, pharyngitis (infection of upper throat), infection in mouth, caries in tooth, internal ear infection, outer ear infection, eczema, dermatitis, dandruff, breast cancer, fungal infection, other cancers like lymphoma etc. If you had flu like symptoms initially then it could be due to infectious mononucleosis too. A CT would give a clear picture of what the swelling is—a lymph node, a cyst or a neurofibroma or lipoma. Take care!
You may want to see about getting a byopsy to rule out cancer.