Swollen lymph node won't go away

[n00bstocks]

I am a healthy 23 year old male who came down with a respiratory illness, sore throat, and throat swelling 2 months ago, mid March. I noticed that one of my lymph nodes was swollen and very tender to the touch. It is the node located at the top of my neck, to the left and up of my adam's apple. I believe it is called the submandibular lymph node. The respiratory illness went away in around a week, but 2 months later, the lump remains.

It's a weird situation, at certain times of the day the lymph node hurts and feels very raw and I can feel it when I swallow, but after a few minutes of hurting it feels much better, as if it's trying to heal and shrink. I also noticed that it is movable, and the next day after palpating the node, it hurts pretty bad. I just don't understand why at certain times of the day the area is painful, and others it doesn't feel bad at all. Should i just leave it alone, or is there anything I can do to decrease the size? Is this cause for concern? I'm afraid I have cancer or something..