i have back problems aswell, i found having the correct recovery between high intens days helped my back pain, so i think CNS work without the right recovery can make your back sore
I find that my back pain(not soreness) comes from my hips getting really tight, so if im runing and my back begins to really start to hurt i’ll stop and strech my hip flexors and the rest of my hip muscles. That works for me since its a problum that i’ve had for at least 4 years and i just now discoverd that my back muscles were trying to compensate for my hip muscles being overly tight. This is my lower back to specifie wat im talking about. Hope this could help.
O in that case, you might want to check into working on back strength, you may not have enough strength for you muscle to hold your spin errect like it should. Have you had x-rays or a cat scan?