Got headache on left side of the head near temples. pain is like a heartbeat comes and goes every second. really hurts. can i miss school. what to do?

Could be dental: I would seek out medical attention first and rule out medical perpetuating factors. After your physician finds no medical issues i would ask your dentist about muscle tension headaches and go thru a consult and diagnosis for tmd. I spend 6-8 weeks with my clients and if your pain goes away which of course only you know i would continue with therapy. Therapy is a plastic appliance that stretches.