I'm such a hypochondriac. I just want some reurance.?

I am a 15 year old female, and for about 8 weeks, I have been getting mild pain in various places on the left side of my head, and occasionally on the right side. They are mild but pinpointed pains. They occur every few days, and have not seemed to be getting worse or more frequent, but I am worried that I have a brain tumor. I tend to be a bit of a hypochondriac, but I am still quite worried. I have TMJ, or at least I think I do, because my jaw always pops when I open my mouth. What do you think is the cause of this headache?