I was stung by a paper wasp nine days ago on the back of my head. Within 12 hours of the sting, two hard lumps developed under my skin on either side of the sting, one behind my ear and the other on my neck at the base of my skull. I was told by a friend that they are likely swollen lymph nodes, but they are still present nine days later and the entire area at the base of my skull is still stiff and tender in spots. Should I visit a doctor or will this go away? It has gradually improved over the last week, it's just that the lymph nodes are still swollen...not sure if that's normal.