I'm not a doctor, but lymph node enlargement can be from many things. It could be from dental problems or a virus or bacterial infection, such as a throat infection, or from allergies. This time of year, allergies are a common culprit. If he has a sore throat or fever or mouth discomfort, or if there is a hot spot in his head or neck, he needs medical attention to check for an infection that needs treatment. If he doesn't get other symptoms, watch the nodes and make sure they go down. I do remember having shotty nodes in my neck for years. Maybe it was related to allergies or my Celiac disease. Not sure.