What Causes Prominent Vein On The Forehead Along With Severe Headache?

So last night I got a rapid headache out of the nowhere. It was a pain just on the left side of my head. It came out of the nowhere and the vein on the side of my forehead popped out. I currently have a mild headache and the vein is popping out. Should I be worried? Or what could be going on?!