Im scared, should i worry?

Im 17 and live in California. My name is Cheyenne and I lost my mom to several different cancers. she was 54 when she died, I was only 13. I recently found out that my mom had Skin Cancer twice before and also had Cervical Cancer. When she was 53 she was diagnosed with Ovarian Cancer and Stomach Cancer. she died at the age of 54, 4 1/2 months later. I also found out that in her family there have been several cases of Brain Cancer, which have only effected the girls of the family. The Brain Cancer skipped my mom and my older sister, and now im really scared because i don't want Cancer, but my doctors have all told me that im very susceptible to to any of the Cancer my mother had, I haven't told them about the Brain Cancer, because I have only found out about just a few days ago. Again im really scared. For awhile now, I have been having these amens headaches, that wont go away for days, even weeks at a time, and nothings helped even ease the pain. I've tried everything I can, but nothing makes them stop. I've also been experiencing pains in my stomach, sometimes I double-over in pain, and sometimes I cant even eat. I've gone a whole week without eating. I can barley hold down even piece of bread, a couple crackers, or even a slice of apple. and I don't know why, I just don't feel hungry, even when I know I should. So please, i need some kind of advice, or anything, before I go to the doctor. Thank You for reading.