Tendonitis. Best thing is to strengthen forearms before doing any heavy barbell curls. Until then try hammer curls. Take ibuprofen and ice if pain persists. This will reduce the swelling. Also, when you are done curling, try slowly releasing your grip over a period of 5-10 seconds. This seemed to eliminate the pain I was recieving after doing preacher/barbell curls.

I use to have this issue, I purchased wrist straps and no longer have the shooting pain.