The most likely causes of pain on both sides of the neck are reactive hyperplasia of the lymph nodes or subacute thyroiditis. Reactive hyperplasia of lymph nodes is most often seen in reactive enlargement of lymph nodes in the neck, which may be related to infections and is often complicated by gingivitis, pharyngitis, tonsillitis, and so on. At the same time, there will be symptoms related to the above diseases, and you may feel the enlarged lymph nodes with your hands, and in severe cases, there will be redness, swelling, and heat sensation at the lymph nodes. In addition, subacute thyroiditis is a kind of inflammation of the thyroid gland mainly caused by viral infection, often accompanied by fever, neck pain, spreading to the back of the ear and under the jaw, if you want to make a clear diagnosis, you need to further check the ultrasound of the neck, which can show the lesions of the lymph nodes and the thyroid gland.