Thanks for your query.
Burning sensation and frequent urination
is suggestive of UTI. Although you urine test is normal it does not rule out UTI because in many a times UTI remains subclinical, no abnormality in urine test may be revealed. I ask you to have a repeat urine examination specially to look for ph, sediments, urinary protein, Gram staining and culture sensitivity. Continue to take doxycyclin HYC tabs along with ciprofloxacin
500 mg twice daily for 19 days. Take plenty of water orally atleast 4 litre/day and maintain local hygiene. If your symptoms persist even after 15 days from now then you should consult a urologist
and at that time ultrasonography
(USG) lower abdomen including pelvic organs and cystoscopy
may have to be done.