well i was hit in the head by a wrench yesterday... my bro was swinging it around it slipped from his hand and hit my head and cut it. i had a headache for 1-2 hours!
An ER visit depends on how bad it is. I'm sure everyone that grew up with brothers and sisters took some hard hits to the head and likely never went to the doctor over it. If I went to the hospital every time I hit my head they'd recognize and know me by name.... wait, they already do (and I don't go to the ER).
Hope your head gets to feeling better, if you show any serious signs of having a concussion then you may want to call your doctor.
No running with scissors, no playing around with wrenches. Poor you! That sounds very painful. I also second going to visit a doc, just in case you have a mild concussion. Hope you feel better soon