Hi, I had a lower back pain from last 2-3 weeks started with unknown reason. I do not remember any major fall or hit to cause that pain. But it was slow in start and started to get worse in a way that I was not even able standup if I take sitting position.  X-Ray results didnt show anything except loss of lumber lordosis due to acute muscle spasm.Taking medication I feel better, but stopping medication it comes up again.  It does not localized to specific location, sometime I feel on left of lower back or right of lower back or center.  Now from few days it sort of on and off pain on lower back along with pain in left side buttock and lower leg below knee.  Do not understand what is the pain actually, please suggest
You have already given the answer to your own question. The low back pain is due to muscle spasm and lumbar lordosis. It often happens due to improper sitting ad lying postures. When the muscles of the lower back go into spasm, the muscles get fatigued giving rise to the pain. Since muscles are not directly visible in an X-ray, the film does not show anything concrete except for the lordosis. You need to do certain back muscle strengthening exercises which can be demonstrated by a physiotherapist. I will insist on getting in touch with one. Hot compress should give some relief. You can take some muscle relaxant tablet like MySpace forte and analgesics as per your requirement.