yeah i think if you do a search on back pain in the aswk the trainer section there are several threads which will have stretches in them.

There is a passive stretch where you lie down on the floor with your feet up on a chair so your legs are at a right angle and your arms lying outstretched to the side.

This one helps let muscle in the chest and lower back release enough to feel the difference in 5 minutes while supporting your back. It's my favourite and i do it just about every day.

Also check Scraps stretching threads