What is the ruling on the prayer of one who has obsessive doubts about his ablution, suspects that wind has been emitted, and frequently forgets what he has said in his prayer? And what is the ruling on seeing yellow discharge after menstruation, and is purification (ghusl) obligatory then?

The questioner's lack of confidence in the validity of her ablution indicates the presence of intrusive thoughts and doubts. Therefore, if she doubts that something nullifying ablution has occurred—such as a release of wind, for example—this does not invalidate the ablution unless she is certain that it has happened. If the forgetfulness she mentioned in the question means that she doubts whether she performed an action or not, and this occurs to her with every prayer, then she is not required to repeat what she doubts having performed. She should not pay attention to it, nor is prostration of forgetfulness (sujud as-sahw) required of her. The best cure for intrusive thoughts is to ignore them and not pay them any attention, as dwelling on them causes them to become ingrained. As for yellowish discharge, if it appears connected to menstruation and before the appearance of one of the two signs of purity, then it is considered part of menstruation. However, if it appears after purification from menstruation, it is not considered menstruation.