I have one month swelling at the base of my neck on the right side. Initially, it was the size of a ping pong ball, over a few weeks it reduced to 1/4 the size of a ping pong ball and today, it increased to 3/4 of a ping pong ball. I did perform strenuous exercised for 35 minutes yesterday. The swelling is soft, and I really do not have pain. Although today my head feels a little fuzzy, almost like very mild flu symptoms. Any thoughts?