The cause of a small lump on the right side of an individual's neck right underneath their jaw is likely a swollen lymph node, according to WebMD. In most situations, swollen lymph nodes are not a cause for concern and they will go away on their own. Swollen lymph nodes can be caused by numerous factors including bacterial and viral infections.
Certain infections in the body cause lymph nodes to swell and become tender and firm. Glands commonly swell when the body is trying to fight off an infection, such as a cold, small cuts or insect bites. One or both lymph nodes in the neck can swell, depending on the seriousness of the infection. Lymph nodes can also swell in other areas of the body including the groin area, behind the ears, in the armpit, on the back of the head and directly below the jaw, according to MedlinePlus.
Lymph nodes will return back to their normal size once the body has fought off the infection. If the lymph nodes stay swollen for weeks or if they continue to swell, it is recommended that the patient seek medical care from their doctor for a proper diagnosis. If the patient also experiences fevers, unexplained weight loss, a swollen lymph node larger than half an inch in diameter or visibly red lymph nodes, they should also seek medical attention.