What Causes Pain At The Base Of The Tongue?

Well, I have pain at the base of my tongue on the left side, but I can't see back there. I also have a swollen lymph node on that side. I have had hairy cell leukemia twice and am a little concerned about these symptoms (not that they have anything to do with HCL but maybe something to do with a different disease). I don't want to over-react but wonder when I should see a doctor.