Sharp head pains really scared?

ive been having the same problem for a year now..its like someone is stabbing me in my head not that i would know what that feels like but i just feel that way. a really bad sharp pain in the back of my head to the right. Ive had mri's also and nothing. it doesnt happen as many times as yours jus maybe 3 times a day. it makes me feel like im about to die. If you find any answers please let me know. thank you