Colbe is right. When the glands under your jaw--which are lymph nodes, by the way--swell, it means that your lymphatic system is working properly because it's fighting an infection. Basically, it means that your immune system is fighting off a cold/virus/etc. Personally, I'd rather have a slightly painful, slightly swollen lymph node and be well than have my immune system fail and me be sick.
~~* laid back, doesn't smoke crack *~~