What Causes Pain In Back Of The Head After Losing Consciousness?

Hey, I drank too much this past weekend. I passed out and loss consciousness for a decent amount of time and was not aware of an event that seems to have taken place directly afterward. I was rubbed down with ice. Following those next couple minutes when I came too everything else is a blur. Now the back of my head has been hurting on the left side, is this cause for concern? Do I need to see a doctor?