probably..or hopefully.. just a strain.. medial epicondylitis... similar to tennis elbow but medially at the forearm.. more than likely.. hurts like all hell.. need to cool that thing down.. ice and light compression first 24 hrs..
Personally i would blast it with NSAIDS for a couple weeks.. like 800mg ibuprofen every 4-6 hrs religiously with food as to not upset or bore a hole in your stomach..
and finally rest!!! That is by far the hardest part... but you can make the problem infinitely worse if you dont listen to your body.. and you can open a whole new can of worms for yourself.. can actually go from a minor strain to a much larger, nagging, life long problem if you dont deal with it and rest it now.