What Causes Itching Sensation In Vagina Of A 4 Year Old?

Good day doctor, I have a 4 year old daughter who complain of itching in her vagina. I took her to the hospital were laboratory test was conducted on her urine sample. Test result revealed staph aureus. She was given a brand of Amoxicillin /clavulanic acid, 228g taken for 7-days. I cream was also given to be applied on the surface of her Vagina. Drugs were used as prescribed. But symptoms reoccurred after about 2 weeks of stoppage. We went back to the hospital another drug was prescribed and used accordingly. Itching continued to reoccur after few weeks of drug stoppage. We tried to maintain high hygienic standard in our toilet as advised by one of the doctors. We currently apply cream each time she complain of itching and she always get temporary relief. Kindly advise on how to stop this itching completely.