straight arm, you better have a good arm guard to shoot trad that way. :D Your elbow hurts because you have a straight arm which does not distribute the bows weight evenly in the arm. (assuming you ment your brace arm not your draw arm). You should shoot with a slight bend in your arm. I like to tell people its like; Stick your arm in front of you like you were going to adduct it (bend it towards your chest), then turn your wrist to the proper angle. In other words, turn your shoulder where your elbow is pointing out almost parallel to the ground, with a slight bend. The elbow on your brace hand should not be pointing down, that would be the orientation if you are shooting straight armed. It will feel odd, but It will help. Bad habits are hard to break. If you go with a heavier bow, you will hurt even more.
Agian, im assuming you are talking about brace arm not draw arm. If its your draw arm, you have probably just developed a little tendenidis. If thats the case, ice it and lay off a bit.