Most common cause is stones in kidney which is blocking urine
pathway. Other causes are changing sexual partners frequently, pregnancy
, diabetes and
of course childhood infections. The urine can also be due to retention of urine anywhere in its flow due t obstruction. The obstruction can be due to abnormality of structures since birth, stones.
So you should get a ultrasound, CT scan done and also some urine and blood tests. Avoid taking pain pills. Drink about 2-3 liters of water in a day.