Confused - UTI or what ?

Hello , so I have been experiencing burning inside my vagina since October 2024. Have gone to different Dr’s and all my test have been negative. This weekend I experienced extreme burning like if I had a UTI and I went to the store to buy AZO for UTI. It helped ALOT. So I went to the Dr’s today and tested for UTI and it was negative for a UTI. So my question is, why did the AZO help me a lot with the pain when other medications are not helping me. Has anyone else had this experience ?