Pain localized in back due to sneezing gives us an indication for disc problem but still to be sure please go ahead with mri.
So that the exact problem can be diagnosed and treated accordingly.
Till than don't do anything to your back like exercise etc and take rest.
Bhujang Asana â 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.
Back Stretching- lie flat, pull one of the knee forward to chest, hold for 3 seconds, then bring the other knee forward to the chest and again hold for 3 seconds. Then pull both knees towards the chest and hold for 3 seconds. Repeat 10 times each exercise twice a day.
Normally sneezing is an involuntary response in which our body get into spinal flexion which increases the pain if it's due to disc problem but that also show you the solution do spinal extension exercise twice a day for a week and you will be fine. And if it doesn't subside consult the physio.