All depends where the back hurts. High up around the shoulders and it could be that you have the bars too low, have to keep the neck up to look forward, hence the pain. Riser bars will help here, as will a shorter stem. Incidentally , do you also get numbness in the hands?, if you do, another pointer to too much weight too far forward and low. If the pain is lower back, could be too short a stem, leading to a rounded back, and hence pain.
I may be of the old school, But I don't see many bar ends in use nowadays. These are usefull to give a change of position on the bike,and do help a great deal on climbs, where you do want weight forward on the bars.