What Causes Intermittent Headaches On The Right Side?

I am having intermittent headache on the right hand side of the head for the last 5 days. The headache started after I was too stressed one day. It wasnt unusual for the headache to appear as i have had similar ones before when I am very tired due to the day's activity but usually they wud go away after a good night's sleep. But not this one.No normal painkiller like panadol etc seemed to work. There are no other sensations like vomitting or tiredness or blurred vision etc. I am having a very good sleep. Not waking up due to the headache. The headache came in bursts of 10 minutes every hour. AFter visiting a GP I was given Voltaren Rapid to be had twice a day one in the morning and one in the evening. This seemd to have improved the headache but it is still not completely gone. After waking up in the morning I have the headache for 20 minutes. Then the whole day goes smoothly. Theheadache comes back in the evenings for 20 minutes after the effect of the tablet goes away. The headache is not excruciating but severe enough that I have to lie down and cant do my work,