There are many reasons of swollen lymph nodes. The lymph nodes are small swellings of lymphatic system. They can swell due to cancer, HIV and also due to bacterial infection. Usually in case of bacterial infection, the lymph node of the surrounding area is swollen. The infection in throat can cause lymph node of neck to swell.
My 14 year old granddaughter has a swollen lymph node under her chin. She was treated for lymphonia 4 years ago. The cancer was in the neck. Blood tests so far are normal. You cannot see the swelling but can feel it. It has been over two weeks. Since the cancer treatments she has had swollen lymph nodes often in the neck area.
My 5 year old has swollen lymph node in his neck. All blood work and X-rays came back neg. His tb test also came back neg.