What should I do? Please, help!?

I know this sounds wired, but it's the truth. I am a 16 year-old girl, and ever since I was 15, I have felt close to death. I feel like something horrible is going to happen to me really soon! I have no idea what it is! I have gotten these feelings before, only about other family members or friends, and each time I get them, something happens to that person(it's never good either!) So, please help, I don't know what to do. Also, there is this boy at my school who is always watching me. A few weeks a go, he asked me to be his girlfriend(He has asked multiple times before), and I said no, and that I never want to be. He gets mad when I respond to his texts the way he doesn't want me to respond. Do you think I should be weary of him?