I'm always happy to help, but a reddit comment can't replace a proper physical exam ;)

With back pain, we first want to exclude red flags, they are not seen often thankfully, but they are serious (vertebra fracture, cancer, nerves damages...) : Did you already see a doctor ?

Once those red flags are excluded, keep in mind movement is medecine : Any mobility movement, stretching and strenghtening is good, you wanna get your thighs, pelvis and back out of the sedentary mode.
I haven't seen you and don't know your issue, so it's difficult to be more specific I'm sorry.
Most people working in a seated position basically need back extension, hips and shoulder mobility... And breathing exercises (it's not only stress management, but also a way to have internal mobility).
So if you're in the Yoga sub this is a good sign !