I FEEL LIKE DEATH IS CLOSE, WHY IM ONLY 19?

im 19 (male) and sometimes out of nowhere i get this erie, creepy feeling like for some reason it feels like i might only have a couple years left, is this normal. And when i get this feeling it lingers until i kinda forget about it. I think it may be related to the fact that my life has been very drab, boring, and somewhat depressing. Ive only had one GF in my life and she stomped on my heart in the worst way possible (ik its pathetic that ive only been with one girl) she didnt like the sex with me (i was a virgin and she had 10 guys under her belt) but she never tried to tell me, she just expected me to know what to do. But anyway i dont know why i get this "death feeling" but it scares me, i really feel like i might die soon, is this happening with other people, HELP PLEASE