What Causes Sore Throat And Swollen Gland In Neck?

I have one swollen lymph node in my neck, around where you can feel for a pulse. I noticed it one week ago becuase I felt like my glands were swollen. I then came down with a sore throat and headache. The lypmph node is approximately 1 cm in diameter, maybe a little larger. I am completely obsessed with it because it isn't going away. I went to the doctor and they put me on antibiotics. They weren't very concerned and have me coming back in a week. I am so scared it is cancer. Should I be worried?