Did this pain start with a certain ball ? I would go to a reputable pro shop and have all you equipment checked to insure they have the same span and pitches. It sounds like you are getting too much strain on your ring finger when you release the ball. Like already said, it could the ring finger span and/or pitch is wrong or the pitch on your middle finger is away too much putting too much strain on you ring finger.
Either way, you can not be sure until the pain goes away. Soak it in ice and wait a week or so before you bowl again. Fortunately, its summer and you will have time to heal before the fall season starts. BUT, have your equipment and your span checked out before you throw another ball.
