I Think I'm Dying!

Hello, I haven't been feeling well for a long time now. I'm only 16 years old. Thoughts of fear. . . of death, keep invading my mind. And I feel that something's not right with me. For nearly a year I've been feeling faintness, I sleep all the time and think only about food, I'm always eating. I can't get enough sleep, no matter how long I sleep. For some time there's been blood coming out of my nose - this is what's scaring me the most.

I've been getting sick every other week for 3/4 of a month now. I've been feeling chest tightness too. I'm also feeling something like pinpricks all over my body. They took my blood sample recently but they said there was nothing to worry about. I don't know what to think, should I talk to my doctor or what. I'm scared and only keep thinking about bad things.