I'm Scared Of Lymphoma!?

(That is not my real name, I'm on my play account, hahah. I'm asking again, because I need answers fast.) Anyway, I have a swollen, painful lump behind my left ear. It's been so swollen and painful, that I have been having very bad headaches. This has been ongoing for 2 weeks. I've been to the doctor, and they said I might have mononucleosis. I doubt that, because the only lymph node that is swollen is behind my ear. They said to come back in a week if I start to feel worse. I have been feeling worse, and it has been a week. My mom will not take me back to get blood work done to actually test for mono. They can't be sure unless I get blood work done. My mom seems to think I am fine. Some of my other symptoms are: night sweats, breathlessness, nausea, weakness, and fatigue, and the one swollen lump. Am I overreacting? I'm a bit paranoid because 2 years ago, my best friend was diagnosed with Hodgkin's lymphoma. I am also 13 years old.