Sounds like you are having problems with spinal loading while in a flexed (lumbar spine) position. This position is one of the most common low back injury mechanisms.
Since it has happened a few times over the past year and seems to have gotten worse during this last flare-up, I think you definitely need to start doing some lumbar spine rehab exercises. Also, you probably are not maintaining your lumbar lordosis (curvature) while performing these exercises, which puts you at greater risk of injury.
If you want to continue performing these exercises, it is imperative that you maintain proper form. Usually you will have to decrease your loading parameters and work on grooving the proper motor patterns. You may have some flexibility or muscle imbalance problems that prevent you from performing the exercises properly.
The chiropractor you are working with hopefully should be able to get you started on a good rehab program.
If you are interested in learning more about low back injuries and how to develop a RH program to help prevent recurrences, then I would suggest that you get the book Ultimate Back Fitness and Performance by Stuart McGill.