Nympho sister has serious problems with sex (incest)

I swear I had never seen anything similar, this kid's sister is a nymphomaniac and has serious problems with sex, the scares that the poor boy takes are not normal, and we all understand that a woman is scandalous in bed, but give you tremors and lose consciousness, is that normal?!, so this boy finds his sister and to try to cure her he fucks her, WTF! Hahaha. Yes, he fucks her hard but it seems that this is not the remedy, the sister suffers some type of seizure every time she has an orgasm ...