hello Deborshi, welcome to HCM
as u have mention about ur pain its due to spasm of muscles.. ur all the tests are also normal..
ur profession is software engineer which makes you to sit for a long period in front of desktop..
1st you need some ergonomically change at your workstation..
2nd you need to do some exercises to keep ur back strong enough to avoid the back pain
.. so that u do not need to take pain killers..
stay fit Deborshi..
consult a good physiotherapist in ur locality to learn proper exercises and few precautions...
u can mail me on firstname.lastname@example.org so that i can guide u about ergonomical changes in ur workstation and exercises also..