Head injury--serious or not?

[mchowkwa]

Hello..
Recently, an acquiantance of mine took a 3 inch binder (weighing approx 2-3 
pounds) and heaved it towards my head.  The binder made contact with the left 
side of my brain (the mathematical/logical side) and the acquaitance weighed 
approxiamently 100-110 pounds.  I am concerned that this impact may have 
caused some brain damage and effected my mathemtical logical abilities, and, 
more importantly could result in the falling of my grades.  Could this be 
possible or is this more of a psychological issue I have to get over?  Would 
my skull be protecting it?  The binder was heaved while my head was still, but 
was NOT able to displace my feet.  It merely contacted my head.  
thanx, please tell me if i am overreacting.