Lymph nodes often swell in one location when a problem such as an injury, infection, or tumor develops in or near the lymph node. Which lymph nodes are swollen can help identify the problem. The glands on either side of the neck, under the jaw, or behind the ears commonly swell when you have a cold or sore throat. If your swollen lymph nodes are tender or painful, you might get some relief by doing the following: Apply a warm compress. Apply a warm, wet compress, such as a washcloth dipped in hot water and wrung out, to the affected area. Mostly it can be bacterial. If not viral. A biopsy can tell us excat reason. Thank u.