Thanks for writing your query.
After reading your post, it seems that your pain is either muscular in origin or has origin in kidney.
Still, you should get yourself examined by an Orthopedician and physician and get the following investigations done :-
1. Kidney Function Test.
3. MRI lumbosacral region.
4. Urine examination.
If there is no abnormality in the kidney, you can take pain killer like Diclofenac
50 mg twice a day after meals along with an antacid like Omeprazole
20 mg and a muscle relaxant
will also be beneficial in relief from pain due to muscle spasm.
I hope this is helpful to you.