Question
For years, I've been doing the excise of "spinal twist", by laying down on the floor on my back, bringing one leg to the opposite side to twist my spine(specially the area of my lower back)while I keep my both shoulders evenly on the floor.  I do this before I go to bed, and every time I do, my spine pops.  Recently, I've started having a lower back pain, not a sharp one but dull pain.  So I told my primary doctor about my excise of spinal twist when I explained about the lower back pain.  Not only my primary doctor but also Physical Therapist told me not to do spinal twist.  I did the menu of some stretch excises PT instructed me to do while I stopped "popping" my spine for a month.  My lower back pain got worse than ever.   PT said that she had no idea what's wrong w/my back.  So I stopped all the excises and did the "spinal twist".  At first, it hurt and popped a lot.  But, that night, I could sleep more comfortably.  Since then, I resumed my usual "spinal twist" before I go to bed.   I would appreciate it very much if you could tell me if I am doing a right thing.... .  

Answer
Violent twisting of the spine can be damaging to the discs (cushions) between the vertebrae.  And sometimes when your back is irritated or injured twisting it can aggravate the condition.  But otherwise, as long as you do it gently and don't force it, the spinal twist is fine--especially if it feels good and makes you feel better afterward.  Keep doing it--but on days when it doesn't feel as good just stop it.

I also suggest you see a good chiropractor, because based on your story it's likely you have some restricted joints in your spine that are resistant to the twist and could be corrected with chiropractic treatment.