Hate that for you. I broke my left, bow arm, elbow when I was a kid and now it limits my bow type and weight cuz it may have a little arthritis. Bad news is you are shooting a 3 piece, with more mass in the bow, and a moderate weight pull. All things for a tender elbow. Are you feeling the pain when you draw or from the shock of the bow?
Bent over rowing works pretty good for exercise. Take about a 20-25 lb dumbell and bend over 90 degrees. Pull the weight straight up and down like you are pulling a bowstring. At least seems to help the back muscles, don't if it will help the elbow, though. Good luck.