Im feeling shakey and weak and always tired.my back of head hurts and i feel like vomiting everythime. should i worry ? whats the problem ?

Your age is???: Your symptoms sound severe enough to warrent a visit to a doctor. Your age would suggest possible different problems in a female. It could be things as diverse as pregnancy to diabetes to an infection. The internet is not a place to make a diagnosis for this. Take care of yourself, and see a physician who can do a proper history and physical and maybe run some tests.