Suggest Treatment For Burning Sensation In Vagina And Back Pain

Hi, I am 50 year old female going through meonpause. I have been experiencing burning up inside my vagina. I do not have pain urinating. I feel like my urine does not come out like a steady stream alot of times almost slow. I do have pain on my left lower side. I did take a test for UTI came out negative. I wake with severe back pain pain on left side. I burn sometimes for hours up inside but not while urinating .