maybe. lymph nodes enlarge or become tender in response to an infection or inflammation in their immediate drainage neighborhood. since your doctor was not able to find a source for this pain or inflammation it would not be inappropriate to have some basic tests first (like a cbc - complete blood count). many things including dental disorders can cause an enlarged lymph node so consider a visit to your dentist as well.
left lymph node under jaw has hurt for past couple weeks. for the past couple weeks the lymph node under my jaw to the left side has been hurting. my grandmother told me to gargle salt water and i also went to the doctor and he said it should be fine. but i don't understand why the pain has lasted so long. should i go back and try to get some tests done?