Hi, I had gone through your query and understand your concerns. At this age first i would think of tension headache
but never so less looking at your symptoms i wold like to rule out high blood pressure
) and if present would like to know the cause of hypertension . kindly go to a physician(M.D medicine) and have a detailed work up .when ever u have a nose bleed elevate your head pinch your nose and breath through mouth for 2 minuets to stop bleeding. Please don't neglect as your young . Have a medical workup done as early as possible.
All the best