There is a small ball on the left chin. I can feel it and it hurts.
This is a lymph node. Don't worry. Generally speaking, tissue infections near the mouth, such as gingivitis and tonsillitis, may cause lymphadenopathy. Lymph nodes are easy to swell, but they are difficult to disappear. When I was an undergraduate, a lymph node swelled up, which is the position. Now I am a master of medicine, and the lymph nodes have not disappeared.