The right answer is Hypochondria.
Hypochondria (or hypochondriac disorder) is a syndrome characterized by excessive and overwhelming fear and anxiety about the health and functioning of an individual's body. An obsessive listening to his body causes the hypochondriac to interpret the slightest observation as a sign of serious illness.
The hypochondriac subject lives in fear or the idea of having a serious illness. He is persuaded to possess signs or symptoms allegedly undetectable by doctors.