It's look like mechanical low back pain .for long term.. You have strengthen the core muscles..... For short term you have to  do hot fermentation, anti inflammatory, rest.... Should  do extension exercises  to maintain  lordosis...

Apply Hot Fomentation twice daily. Avoid bending in front. Postural Correction- Sit Tall, Walk Tall. Extension Exercises x 15 times x twice daily - lying on tummy, take left arm up for 3 seconds, then bring it down, right arm up for 3 seconds, bring down. Bring right leg up, hold for 3 seconds, bring it down. Then right leg up and hold for 3 seconds and bring it down. Repeat twice a day- 10 times. Bhujang Asana -- Lie flat on your stomach, keeping the palms out, bend the neck backward, take a deep breath and while holding it for 6 seconds, raise the chest up. Release breath and relax your body. Repeat the exercise 15 times twice daily. Core Strengthening Exercises- Straight Leg Raised With Toes Turned Outward, repeat 10 times, twice a day.

As MRI report is not showing any significant injury, then there may be some other cause like soft tissue tightness etc, which may occur due to Manny reasons like posture/ deficiency ect.

U can take few physio sessions to correct ur back...

U have to start physiotherapy treatment and take precautions as dr suggests u. After long time work, pain start due to muscle weakness so avoid it. Good luck.