Welcome to Ask The Doctor.
You seem to be suffering from Acute Muscular back pain.
For muscular pain, i advise following:
1. A combination of pain killer and muscle relaxant containing Diclofenac and Thiocholchiside.
2. To do hot fomentation of the affected area.
3. To apply Diclofenac ointment locally.
4. To get physiotherapy done particularly Ultrasonic heat massage.
If the pain doesn't get relieved you would require MRI LS Spine for the same.
I hope it helps.
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