Although a kidney infection can manifest symptoms such as back, side (flank) or groin pain...there are a number of other symptoms that might point to a UTI. The urge to urinate recurs quickly, and painful urination are the most common signs of a UTI... and soreness may occur in the lower abdomen, back, or sides. In order to confirm this possibility, you can visit your doctor to rule it out via a urine analysis.

Then, if you are simply experiencing common lower back pain due to your job, I'd suggest that you look into changing your posture at work and strengthening your abs. This can help do wonders for mild lower back pain.

you need to check your urine, go for the urine test and then only anybody can tell what exactly the problem is .