Golfer's elbow, is very similar to tennis elbow, except it happens on the inside of the arm rather than the out. Golfers elbow, or medial epicondylitis, is a repetitive use injury. Just like tennis elbow, it causes pain due to inflammation and damage to the tendons and muscles in the arm - a result of vigorous or repetitive use.
Treatment for Golfer's elbow varies - some doctor's recommend lots of stretching as a method of therapy. One thing that may help is a brace specifically designed to help compress the musculature in the arm, preventing sore tendons from rubbing against each other and causing you pain