Thanks for your query.Based on the facts that you have posted it appears that you have noticed small white particles in your urine and have been treated with antibiotic .
You have been under treatment of Urologist
who has carried out almost all necessary investigations and fcould not fine any obvious reason for your problem.
The white particles are most likely dis- sqamated epithelial lining of bladder mucosa as a result of chronic infection of the bladder.
Please get your urine culture done to trace the organisms causing this infection and take the appropiate antibiotic as per culture report.
Ensure to drink more water to keep your urine dilute.
Thanks and Regards.