Is it possible to act upon the saying that the period of possibility for menstruation is 10 days from the sighting of blood? And is it permissible to act upon the opinion that does not consider yellow or turbid discharge as menstruation at all, even if I am not convinced by it and modern medicine proves the opposite, especially since this causes me many problems and repeated ghusl?

The question is ambiguous, and we have clarified in previous fatwas that the maximum duration of menstruation is fifteen days according to the majority of scholars, and ten days according to the Hanafis, which is a weaker opinion. Yellowish and brownish discharges are not considered menstruation at all by some scholars, but the prevalent opinion with us is that they are considered menstruation during the accustomed period and if they are continuous with blood. If someone you trust for their knowledge gives you a fatwa that contradicts what we have mentioned, there is no blame upon you for following it, but you are not permitted to act upon something you believe to be contrary to the Sacred Law.