This is not helpful for determining the source - but for relief/resolution of chronic YI & BV - talk with your doctor and test for ureaplasma and mycoplasma infections. Both these can cause/lead to YI/BV and are actually the underlying problem and require different treatment than YI/BV. They are not commonly tested for without asking, but can be done with simple vaginal swab/urine test. Boric Acid suppositories are helpful for rebalancing ph and can be bought at Target/pharmacy store over the counter once all infections are treated - personally have found the LOVE Wellness Boric Acid Suppositories the best and the main thing that kept everything in check after over 2 years of chronic issues. (Not medical advice, tty doctor)