Thanks for your question on "Ask The Doctor".
It’s now more than 3 weeks you are having pain in lower back, ththis could be Pelvic inflammatory disease, an infection of pelvic organ.
There is also a possibility of lumbar spondylosis in absence of history of injury to lower back.
You may be having a muscular sprain.
It seems more like a muscular pain that you are describing.
I would advise you to try some heat compress and local anti-inflammatory gels.
However, if the pain does continue I recommend you to see your family physician for a physical examination.
Wish you a good health!
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