Your arrow rest could be too far right or left. Your nocking point could be off. A lot of thing could be wrong. Len is one of the best in the business. He will fix whats wrond and explain everything to you. So not only are you getting your problem fixed you will be learning in the process. Things like this will make you pull your hair out trust me. Have someone help you tune your bow, and you will be shooting so much better. Your confidence hill be way higher, and youll have a lot more fun. Here is some info on bow tuning. but definatly see Len you wont be sorry.
http://www.eastonarchery.com/downloads/zips/tuning_guide.zip Youll need Adobe acrobat to open it