Is the Hajj valid despite uncertainty in determining istihadah (non-menstrual vaginal bleeding) based on the customary days of menstruation, and what is the ruling on prayer and fasting in the current state of bleeding?

If the days of bleeding do not exceed fifteen days, then you are in menses, not istihadah (prolonged non-menstrual bleeding). If you performed tawaf while menstruating, your tawaf is invalid according to the majority of scholars. You are now required to go to Mecca to perform tawaf al-ifadah and sa'i, and then perform the second tahallul (partial desacralization). Your husband must refrain from intercourse until then. What occurred in terms of prohibitions due to ignorance is pardoned. Some scholars consider the tawaf of a menstruating woman valid, with the obligation of offering a badanah (camel or cow sacrifice), but the fatwa adopted by us is the first opinion. There is no blame upon you in following someone you trust. As for yellowish or brownish discharge during the customary period, it is considered menses, and you should refrain from prayer and fasting for it.