Your back pain could be structural or muscular related. I doubt it's nervous.
Get an xray, just to make sure you don't have scoliosis or any other spinal cord abnormality, and then maybe get a CT scan and an MRI to make sure that all the finer details of the bones, muscles, ligaments, tendons, and nerves are in good shape.
I would recommend seeing a physical therapist and getting evaluated for general muscle strength... and then getting exercise recommendations to strengthen the weaker muscles in your your lower back and thighs.
And in all honesty - it's very unlikely for a Sir-Mix-A-Lot approved booty to be causing such pain. It is most likely muscle weakness in some parts, caused by strengthening of muscles in other parts due to your sport. Mental conditions such as anxiety and depression can cause unexplained back pain too, but hopefully you don't have any of those.