I have a headache on the left side of my forehead that comes and goes....its more annoying than painful. should i be worried??

Be more curious.: I'd be more curious than worried. A persistent, unrelenting headache should be defined, at least perfunctorily. Could be sinuses, tension, migraine. Could be something more significant, although your young age would generally argue against that. I would generally advise an investigation just to be sure - blood testing and an MRI of the brain.