Lump in neck for about a month. had bronchitis about 3 weeks ago. tried zpack&amoxicilin and lump still there about size of nickel. what could it be?

Lymph node?: When did it appear? How big? Is it getting bigger, staying the same size, or slowly getting smaller? If it appeared when you were sick with the bronchitis, i would assume at this point that they are related. It can take 1-2 months for the lymph node to shrink after an infection. As long as no new lumps appear, you are feeling well otherwise, i think you could watch it. If not, go see doc.