Constant backpain. Sides at night.

Some more information is needed before I can give proper advice. Are you in a desk based job? Do you sit for Long hours? Have you had any injuries? Is it only back pain or do you also have pain down legs? If it is only back pain, then your posture is the main culprit. You have to maintain a good posture at work,take regular breaks at least every 20mins to get up from your chair to stretch. You need to adjust your work environment to make sure there is no significant stress on your lower back. Do exercises like yoga, stretching, Pilates and core strengthening. All of this will help in strengthening your lower back. Take painkillers as needed. These things take time to work, so make sure you do these regularly for a few months to see the benefits. If still now helping, then you need to see an Orthopaedic Spinal Surgeon.