Headache are often a symptom of a larger condition. The causes of a headache can be numerous. According to your description (severe headache at the back right hand side going across the top to the left top), you might be suffering from a migraine. Your doctor has given you symptomatic therapy, i.e just pain killers as ibuprofen. However, if the pain continues you may request further examinations such as an EEG (electroencephalography) or CT scan of the brain to find out the exact cause of your headache.