What are these headaches and what is causing them?

a while back i started getting headaches, i assumed it was just tiredness, but then they started to come more and more and each one i got it was worse. it is like a throbbing pain in one side of my head, i feel like i have to look away from the light. and then today all off a sudden my eye sight went really dodgy and i started going a bit blury and seeing clouds in my eyes and stuff, and then about 20 minutes later this sudden headache came on, i had to go to my bedroom and hide in the dark, i was crying in pain. i took some parecetomal and after about an hour or so it eased off. please help me?