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.