Submandibular Lymph Node Swelling

Hi, I around two years ago I noticed an enlarged lymph node under my jaw. I knew I needed a root canal on one of my teeth directly on top of it. I had the root canal done, but the lymph node under my jaw is still just as large. It's almost the size of a marble, and I can move it. It's not fixed. It's under my jaw and I can grab it and move it just to the outside of my jaw. Sometimes I have pains in my jaw where I had the root canal but I guess those are just phantom pains or something. I find myself constantly worrying and messing with my lymph node and figured I should probably go see a doctor or go back to my dentist, I'm just wondering what to expect. I'm 22 in decent health and this is the only lymph node that is enlarged.