What Causes Tender And Swollen Lymph Node Behind Ear?

I have a very tender and swollen lymphnode behind my right ear. I also will b having a partial thyroidectomy next month because I have a right nodule that is suspicious for Hurtle Cell thyroid cancer, but we won't be sure until the pathology comes back after surgery. I'm not sure if I'm just getting sick, or is the swollen node related to my thyroid problems?