Urine burning & Vaginal pain.

My mom aged 57, BP and Diabetic patient, 5 months back made bilateral RIRS. Past one month she is suffering from urine burning sensation, pain and pricking whole day. Consulted two urologist, the one who made surgery and gynec for uterus abdomen scan, and took RfT elecrolytes, Lft, urine routine culture report is normal. Took antibiotic for 5 & 7 days, till then pain and burning got reduced a bit ,but after that it started again, now asked to apply evalon ointment for alternate days till one month, 14 days passed by, still pricking and pain persists especially during late evening to midnight/early morning. Frequent urge to urinate, also 4-5 times in the night. No proper sleep. What could be the reason? Should i consult some other specialist?