Hi. You have not said upper back or lower back so I cannot say if your problem is same as mine. I had pain on my right side in my upper back, almost in/ or little below shoulder area which was also starting to radiate to the front. It felt like sore muscle just like you are describing. I went for check-up. and was told it is posture related. i work 8 to 10 hours on computer and strain on my right arm was causing the pain. I was on painkillers for about 2 weeks. I also changed my chair. Doctor also advised physiotherapy
but I never went for tht. Now my pain is better. But comes back if I work long hours on several days.But if you are suffering from low back pain
it is probably something different from what I had.