There are various reasons, depending on mechanism of injury and age. The chronicity or period of pain also accounts for how much relief you obtain from such treatment options.
Hence there is no good answer unless a proper history and examination is undertaken.
However, most of such causes may he attributed to facetogenic back pain (for ages above 50) and intractable muscular pain for the younger ones. Disc related pain is very specific in the midline and may affect all age ranges. Of course, insidious causes have to be ruled out with MRI imaging.
If medication and simple physical therapy does not work, then interventional techniques may be helpful. Pain intervention involves putting needles at the pain source (under xray or ultrasound image guidance) and injecting medication or therapeutic agents to relieve the pain generator. Thereafter physiotherapy may help to prolong the beneficial effect.
I hope this helps