Another thing you might want to check is the position of your bow arm elbow when you draw. I've seen a lot of new shooters smacking their arm because their elbow was pointing down instead of to the side.
You can check this by extending your arm and placing your bow hand on the corner of a door frame ( base of thumb on the corner with the V or web pointing up). Now, look at your elbow. You'll notice that, if you roll your shoulder, slightly, so that your elbow is in the 3:00 position instead of the 6:00 position there is a lot less meat in the path of the string.
This is a simple fix, if it applies, and only takes a short time to gat used to.