Hi Lankster! Welcome aboard!
The lymph nodes in my neck are pretty much permanently swollen and sore. It's common, as the theory goes that the immune system may not be working quite right in CFS patients. However, if this is a new symptom for you, it wouldn't be bad to check with your doctor. I'm just thinking since only 1 node is swollen, and not both, that is a little weird. Usually, when 1 node is swollen, the partner of that node is swollen on the other side too. (Does that even make sense? lol) I think it would be good for you to mention it to your doctor, just to make sure. I'm sure it's nothing, but a good friend always used to tell me: "is it something you'd go to the doctor for if you didn't have ME? Then go, and get it checked out just to make sure."