Weird headaches? Left side of head? Vein pulsing?

So I usually get headaches every day and I get different kinds of them but recently I've noticed the headache that hurts the worst feels like this:

The left side of my head hurts the worst, and a vein on my temple pulses and throbs. I can feel it no matter what I do, but when I put my fingers on it, I can really FEEL the vein. It feels huge, and I can feel each pulse and throb just as easily as you could feel fingers under a blanket poking and prodding your skin.

Then when I touch the right side of my temple where a vein is, I don't feel a pulse.

Any ideas?