I Think I Might Have a Brain Tumor...

But i'm not sure, I have some of the symptoms listed, maybe i'm just paranoid but i'm getting scared. I get headaches at least once a week, my memory seems to get worse, I get nasaeus at times, I lose my temper more easily, and I times I get a ringing in my ears. The other day, in gym, I was losing my breathe, my heart was pounding really fast and I could feel it, and all of a sudden it went into the back of my head, and my nurse said she thinks I should consult a doctor. I also have a somewhat large bump on my head. What should I do? Does anyone know if I could have a brain tumor?