What can symptoms like swollen lymph nodes and headaches mean?

Detecting illness: Lymphatic system absorbs/carries things too big to go into the arteries and veins like bacteria eaten by white cells and digested food.Lymph nodes "taste" the lymph to see if anything bad is there like bacteria, viruses, cancers, etc. When it detects a problem, it alerts the immune system and your body reacts (headaches). They enlarge in response to the inflammation they create when they react.