Hello, commonest cause for the symptoms you describe is viral infections. Lymph node enlargement canbe seen in both viral and bacterial infections. Low grade fever with more nasal congestion and other symptoms are suggestive of a viral infection. some thing like infectious mononucleosis. You have a contact history also.( your son ) Strep infection would have high fever with other syptoms but less nasal congestion. Also your throat will have white plaques or pustules. You can have adequate bed rest, loratadine or fexofenadine, paracetamol, warm beverages, After 4 days if symptoms are not subsiding ,get your blood tested. Because if it turned out to be bacterial ,strep needs antibiotics. Hpoe this helps. Thank you.