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.
Please discuss this with your doctor.
Hope this helps. Do let me know if there is any thing else and keep me posted. Take care!