What can I do about this indented vein? (photos)

I've attached a photo to show you but I'm only 23 and I have this long indented vein that has shown up over the last 12 months and will NOT go away. If you run your finger over it you will see that it has left a long indentation along the side of my head. It's impossibke to cover wih makeup and i really just want it gone but just also wonder why has it shown up in the first place? It causes me pain all the time, it's often warm and I can feel it throbbing. When I talk or laugh or cry it bulges. Help!