Pain in the lymph is most commonly caused by two causes, as follows: 1. Inflammation in the organs or tissues near the lymph nodes, which spreads to the local lymph nodes, and also results in swollen and painful navel. There are two common locations, the first being swollen lymph nodes in the lower jaw and upper neck. The most common are acute pharyngitis, acute tonsillitis, or acute bronchitis, which may be induced. The second is swollen and painful lymph nodes in the groin, which is commonly caused by soft tissue infections of the lower extremities, especially lower extremity dermatitis, or toenail sulcus, which can trigger swollen and painful inguinal lymph nodes. 2. Malignant tumors appear in the organs near the lymph nodes, which affect the nearby lymph nodes through lymphatic metastasis, resulting in swollen and painful lymph nodes.