Try this mobility exercise from John Singleton (and Anna Hulda)
Back Pain. Sometimes simple is best. Back pain often causes troubles reaching forward, those who have had back pain can testify to this, picking things up off the floor, putting socks on in the morning and similar movements can often elicit a pain response. Once this movement becomes painful, people can then start to avoid the specific movement. This can lead to altered movement patterns and possible further complications. If you can reestablish a similar movement pattern in a non painful way you can help to restore the full motion you have lost. For those who are suffering from acute back pain restoring the motion in a non painful way is an extremely useful way to begin the recovery process. The best way to achieve this is to start via non weight bearing exercises such as kneeling on the floor (as in the video) or sitting down, then progressively building to increasing weight bearing movements. Back pain can be extremely painful, however reestablishing is a crucial component of the recovery. This video is from the 2015 @crossfitgames where @annahuldaolafs had suffered an episode of acute low back pain however managed to finish the Games, partly due to reestablishing non painful movement but mainly because she is an Icelandic beast ?