It may be due to elevetaed blood pressure check your blood pressure for 03 consecutive days.
It can be due to vision problems if you think that you donot have any vision problem check once your vision.
It can also be due to chronic sinusitis
have an Xray PNS to rule out sinusitis.
Also have blood test
named as Blood CP to check for Hb levels.
If all the things are fine then just take Tab. Synflex 550 mg twice a day for 03 consecutive days.
I hope I am successful in solving your query If you have more you can ask me.
Dr. Azhar Sattar