What Causes Short Term Memory Loss, Headache And Dizziness After Hit On Head?

K...I got hit in the head at my hockey game yesterday and once I did I had no recollection of what day it was, or what I did during the day. Granted after about 20 minutes I was able to remember. But even now I cannot remember the first 2 periods of the game. And all day I have had an annoying headache and some dizzy spells. If anyone can help it would be deeply appreciated... thank you