Does a person have the absolute choice in determining the type of discharge (mani or madhiy) even if he predominantly believes it to be mani? And if he chooses to consider it madhiy and prays, then signs of mani appear later, does that confirm the discharge of mani, and must the prayers be repeated?

If a person doubts whether the discharge is semen or something else, he has the option to choose, and this includes cases of strong presumption (Ghalabat al-Dhann); because doubt (Shakk) according to the jurists is indecision, whether the two possibilities are equal or one is preponderant. What was mentioned about a pimple appearing after semen discharge, we do not know of any religious or scientific basis for it. If a person chooses and considers it madhiy (pre-seminal fluid) and then becomes certain it was semen, he must make up the prayers he performed after making that choice and before performing ghusl (definition) (ritual bath).