Headaches, Confused, No Energy, Eeg, Unstable Vision

Hi...
I fainted 2 days ago for nearly 15 minutes. Mi parents sent me to an internist doctor and I told him that I had a bad headache, my head felt like turnign around, and hten slowly, I cant hear, everything went black and finally, dropped to the ground as I have no energy or control over mi body. My head felt like spinning and really heavy that I felt like dropping it.... After a while I felt like throwing up, but I didnt.
The next day, I went to do brain mapping or eeg and they didnt find anything wrong with me. The doctor said that I fainted because mi blood presssure dropped and I dont understand why. I wasnt freaked nor scared.
These few days, I felt very confused when I think about something, this has never happened to me before, and I felt like I have no energy.
I donot wish to tell mi parents that I am still not feeling well, because they are really worried about me.
I used to have a younger brother and he died because of brain cancer, I was 13 and he was 12. Are headaches and unconsciousness part of the symptoms of brain cancer?
Whats wrong with me?