I know that the lymph nodes are filters for your body, I would advise you to talk to your oncologist just to ease your mind, and he should know your concerns.
I pray for your remission. Blessings to you
Please go and get yourself checked. It may well be nothing more than an infection of some sort, but if you have lung cancer you shouldn't have your immune system compromised if possible.
I always act on the better safe then sorry philosophy.