A lot of back pain, regardless of where is is felt, stems from the large Bundling of nerves in the cervical spine and in the sciatic nerve bundles underneath your glute muscles.

Do not stretch your spine, as your structure is likely weak, and you can further damage your disks/vertebrae and the nerves therein by improperly applying changes to where the pain resides most frequently.

I suggest you look into foam rolling, and fasciae work in the glute/hamstring areas first. There are a lot of mobility youtubers that talk all about different techniques.

Also I have been studying the effects of LaJin (Traditional Chinese stretch series) and so far found the prolonged relaxation in the fascia to relieve chronic pain, and uncover structural improprieties that are the root cause.

Here is a long write-up over self healing with paida-lajin (拍打-拉筋 Basically slapping-stretching). http://www.dontow.com/wordpress/wp-content/uploads/2013/09/P...

As for how long it takes to get better... growth and entropy are in opposition. It may relieve your pain day 1 but it may come back halfway through the next day, it may take 6 weeks to feel the deep relief. Your structural damage could be well beyond simple tissue degeneration and nerve pain, in which case self treatment is not advised. You should have an MRI taken if you believe yourself to be in later stage deterioration of the affected area.