According to the symptoms you describe (variations of headache) I can’t precisely identify exact causes because there could be a million reasons for headaches, from the easiest (physical or mental fatigue) to the most severe (brain tumor). You first alleviate the pain temporarily using paracetamol, aspirin, etc…). If these medicine don’t help and the headache becomes unbearable, you might consider visiting your GP for doing some basic examinations such as measuring the blood pressure with standard blood analyses. Further examinations from an ophthalmologist, ENT-specialist or neurologist may be requested, if necessary. Finally, a CT-scan is the last diagnostic procedure that can be done to diagnose the cause of your symptoms.