Could I have a Concussion? ?

Three days ago I was rough housing with a few friends I was struck in the head with a house phone pretty hard. I was dazed at first and slept a few seconds later. When I woke up I felt dizzy and ha a horrible head ache so I went for a trip to the ER they did a cat scan and all came back normal. Doctor didn't really say much other than that and I was discharged. Still have head pain only in the area in which I was struck and a little pain behind my left eye. Could I possibly have a concussion or after affect of the impact ?