Does excessive involuntary throat clearing during prayer and obsessive doubt about the salutation after finishing it invalidate the prayer?

Humhuma (clearing the throat) due to an overwhelming urge or forgetfulness does not invalidate the prayer. If someone experiences excessive doubt to the point of it becoming like obsessive whispers (waswas), they should not pay attention to it, nor should they perform what they doubted they missed, nor should they perform the salutation (taslima) they doubted. Their prayer remains valid. A single taslima is sufficient, and turning the head with the salam is a Sunnah (definition), not performing it does not invalidate the prayer. The best cure for obsessive whispers is to disregard them.