First of all , please read following tips:

Please from this moment add stretches of your back to your daily routine. Take it as the short term and longterm investment. After heart and brain, chord could be considered as one of main structure, as all spinal nerves bringing signals to particular organs and muscles come out from your spina cord between your vertebrae. Waiting for long time for proper moment can bring in the future serious diseases.

I recommend to add daily 2 x 15 minutes of stretches than 1 and half hour once a week in yoga classes. After one week your body is already in deficit of stretches. 

Take exercise as a reward and really long term investment. 

If you currently do not feel comfortable with your back, please be kind to your back, do not try to solve everything in 5 minutes. Take your time for exercises. 

Not all exercises are for everybody. Our vertebras, disks and spinal cord is different in each human considering muscles, status of vertebras, way of use, way of life and so on.

Listen to your body. When you feel pain do not push against and rather release pressure.

Find your exercises which suits you and help you best.

If you have already spinal cord injury please discuss with your doctor or physio-therapeut extent of exercises to avoid further damage.

Please consider and ad to your daily work, small 3-5 minutes to stretch your back to protect your body from creating spasms of spinal muscles. 

You can add shoulder rotations, head rotations, shoulder squeezing, specially when you are sitting all day behind the computer and you neither realise how many hours you are in same position with head in the forward position. Specially when there are huge expectations which are put on us, we regularly forgot to breathe, drink, eat, and of course we forgot to stretch during the day. As a results, our back muscles after long day are already in the spasm and probably we are feeleing pain in the evening. And you can imagine that day by day , your back is getting worse.