Hello Thanks for query . Severe pain in back with brown coloured urine strongly suggest presence of stone in kidney or ureter and needs to be investigated . Please consult qualified Urologist for clinical examination and get following basic tests done to confirm the diagnosis. 1) Urine routine and culture. 2) Ultrasound scanning of abdomen and pelvis 3) Renal function test . In the mean while start taking broad spectrum antibiotics like Cefixime and urinary antiseptic like Nitrofurantoin along with antispasmodic like Cyclopalm twice daily and urine alkalizer thrice daily. Ensure to drink more water . Further treatment will depend upon result of these tests and final diagnosis and size and site of the stone . Dr.Patil.