Common causes of headache are , sinusitis, anxiety, tensions, migraine, cold, cluster headaches, high BP. 
Get ur blood pressure checked too. 
If nasal congestion, take steam inhalation twice daily. Take over-the-counter painkiller if intolerable pain. 
If any other symptoms eg vomittings,black outs,intolerable to light..migraine to be ruled out. Take adequate rest in a quiet  room.
Hope this helps u. If required, consult with details.