HELP PLEASE. ANXIETY OR TRU FEELING?

hey, right now i feel like crying. i have this weird feeling that something bad is going to happen, and dat i might die. 2 years ago i had the exact feeling and my grandad died,on the same day he died my feeling went away, and now im reallly scared dat i mite lose a loved one or dey might lose me. i have been sick 2 wks ago from kidney infection and strained muscle im better now, thanks to god. but sometimes these feelings are so strong that i cant even concentrate. When i fall asleep i wake up suddenly, i have no bad dream whats so ever, this feeling disappears in the daytime and comes back at night, im scared soo badly. i also panic for the little cases, when i was sick i panicked so much i thought i might have cancer, and i got sicker, but that thought is clear now. im 14 now and have currently no health issues. i also feel like sometimes i dnt have a heartbeat and that my body is shivering i get cold and i breath rapildy, can u please help me and share ur experiences with me, thanks that would be great:) ooh and have u ever felt this way before and if yes what happened?..thanks so much! all this feeling started when my bestfriends grandad ped away 2 wks ago and i still feel like dat, please help!