Hypochondria

Hypochondriasis is a mental disorder characterized by a preoccupation with the fear or belief that one has a serious physical disease based on the incorrect and unrealistic interpretation of bodily symptoms. This fear or belief persists for at least 6 months and interferes with social and occupational functioning in spite of medical reassurance that no physical disorder exists. These symptoms are characterized by high health anxiety and health-related preoccupations but that occur either in the presence of significant somatic symptoms, or in the absence or with minimal evidence of such symptoms.

Source: American Psychological Association.