The kind of pain you are facing might be directly related to your job as you have or might be sitting for long hours and not getting time for exercises or walk.
As your pain is from last few days only.
Just do hot fomentation (hot pack) for 10 min or so and take rest.
Also use back rest while sitting on chair.
Once you are comfortable start back exercises
If not relieved in 3 to 4 days please visit your doctor.
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.
Hello... Lower back pain could be due to paraspinal muscle spasm , intervertibral disc bulge or herniation,damaged bone or ligament,radiculopathy ( small nerve root irrigation) ..it s not possible to comment without x ray ,MRI, ... Improper posture while working or sleeping can also aggravate back pain consult orthopedic surgeon
Well my friend, past few days as per my knowledge were quite hectic as you are a professional CA and its TAX filing time . You must be working a lot. and specially in odd hours and in odd sitting positions. which is uncommon in daily routine tasks. I advise you to take warm water bath and stretch your body a bit. basic bending and twisting.(try touching toes / ceiling, and turn sidewards hold for 20 seconds and release ). as far as medicine goes avoid as much as possible, if unavoidable you may take himcospaz y himalaya store (an anti-spasmodic drug that will release the muscle tension and will help you relax).
Also, make sure despite workload , you must use proper ergonomics, and consult an Occupational Therapist / Work space ergonomics to help and guide you so that the problem does not reappear.
Use a good and Comfortable ergonomic seating according to your need and budget. Consult Immediately. STAY HEALTHY