Hello and welcome to HCM.
I understand your concern about your granny.
She has had all her cultures negative but still facing burning sensation in urine.
It can be due to other gynaecological problems related to pelvis like
endometriosis,malignant changes in internal genital lining or simply
vaginal dryness.
If I were your treating doctor,I recommend,
-Referral to gynaecologist for doing
endometrial biopsy and USG pelvis.Further management will depend on the diagnosis.
-Drink plenty of water
.-Empty bladder frequently.
-Include fruits juices and 2-3 servings per day of vegetables in your diet for much needed
vitamin A and anti oxidants.
-
Estrogen cream for local application. (prescription drug)
Hope this information helps.
Thanks and regards.