Burning micturition

Patient: Dear Sir, one year ago I had burning micturtion, I met a urologist and after investigation he diagnosed my condition as BPH and gave e cardura and antibiotic, my condition improved.3 months ago again the condition started and I did may test including kidney and pelvic scan and the only positive finding is slight enlargement of the prostate. urine is clear no blood or pus cells, PSA 1.5, no stone.The doctor put me in antibiotic ciprofloxacin and cardura, but no improvement. the pain sometimes very sever and sometimes decrease.Now on cardura and azithmycin 500mg for 3 days every week and now the 2nd week, also no improvement.thanks