i got this when i started doing a biceps exersice, like concentration curl only it wasnt quite the same, i think its the Branchilis (sp?) that are sore, its a muscle like between the biceps and the under arm.
thats all i got.
You could have tennis elbow which is very serious. I'd give it a few days like nobody said and if it's still there get it checked out. Tennis elbow takes a long time to recover from if you don't get it treated as early as possible.