My Doctor once told me that swollen lymph nodes are also a sign that your body is fighting off an infection. He said it could be as simple as a slight infection in a knick from shaving. I had one on my groin and right away I panicked that something else was wrong. He of course was right that time and it did go away on it's own in a week or so.
My initial symptoms of TMJ actually began with a swollen lymph node. My specialist explained the lymph node as an indication that my jaw joint was getting worn down and therefore causing bacterial or viral infections. At first I thought I may have leukemia or cancer. But after taking antiobiotics for a week, the lymph node completely went away.