Hi,
Welcome to the ehealthforum and I am really glad to help you out.
It is not normal to have swollen lymph nodes for so long. Lymphadenopathy (swollen lymph nodes) is usually caused by a viral or bacterial infection. Other causes include allergic reactions, arthritis, cancer, metabolic diseases, and an overactive thyroid (hyperthyroidism).
T find out the cause, a FNAC (fine needle aspiration cyrtology) needs to be done. FNAC is aspiration of the material of the glands which is done by a fine gauge needle (22 or 25 gauge) and a syringe.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.