Chronic swollen, sore lymph node and tonsil on one side, what could it be?

I have been having an ongoing problem for about 2 months now. One side of my neck and tonsil will swell up and become very sore and tender. It lasts about 2 weeks then goes away for another 2. It then reappears on the other side, same symptoms. This is the 3rd time is has happened like this. They have tested me for strep, negative. They are testing me today for mono but I have no other symptoms beside the very sore swollen tonsil and lymph node, and its always just one or the other. Has anyone had this problem? Any suggestions I can make to my doctor to test me for? I am a smoker so I am concerned that it could be something worse than a viral infection.