Does rinsing what I thought was the outer part of the vulva, but later turned out to be its inner part, invalidate the fast? Do discharges that exit without sexual arousal nullify ablution and make clothes impure? Does the exit of water used for istinja' (ablution after defecation/urination) from within the vulva necessitate repeating istinja' and changing clothes?

We say that the apparent part of the vulva is what becomes visible when a woman squats to relieve herself, and the inner part is what does not appear in this situation. As for explaining this with scientific terms, it is not within our specialization, and you can consult the medical consultation section of the website regarding it. We advise you to cast away obsessive thoughts and disregard them.