This appears to be hypochondriasis, which is a preoccupation with the belief that you have or are in danger of developing a serious illness. Many people focus on bodily functions or sensations, or they worry about a specific organ or fear getting cancer or another disease.
When they have hypochondriasis, people often believe that any discomfort whatsoever means bad health. They misinterpret normal bodily sensations (breathing, heartbeat), minor physical abnormalities (skin blemishes), or physical sensations (headaches, stomachaches) as dangerous.
But our “noisy” bodies create all kinds of sensations that aren’t dangerous. Think of the human body as a complex machine like a computer or automobile that produces clicking, whirring, and other noises even when it’s working properly.
A healthy body also produces normal physical symptoms that might be uncomfortable, painful, unexpected, and unwanted. It might also include changes in vision, heart rate and blood pressure, breathing, balance, or muscle tone. When you misinterpret these as symptoms of a terrible disease, it makes you worry. This explains why medical tests come out negative: The sensations are real, but they’re not symptoms of a disease.
People with hypochondriasis are often reluctant to seek mental health evaluations because they believe very strongly they have unexplained medical illnesses. And the urge to call the doctor grows intensely.
Reassurance from doctors doesn’t help, though. Why not? When you become anxious, you may experience a rapid heart rate, difficulty catching your breath, dizziness, the sweats, or seeing spots. Although these sensations are not dangerous, if they occur right when you’re anxious about your health—wham! It adds fuel to the worry fire.
Seeking reassurance from a doctor and checking your body may actually prevent you from realizing that you are not sick. But you become preoccupied and more likely to notice subtle sensations that most people ignore. A vicious cycle develops of noticing a sensation, misinterpreting it as threatening, becoming anxious, and seeking reassurance—which leads to further preoccupation and worry with the essentially harmless sensation.
Under a skilled therapist’s assistance, you will learn the role that your thoughts and behaviors play in generating health anxiety.
Effective treatment requires that you correct your threatening interpretations of certain body sensations and eliminate compulsive checking and seeking reassurance. This treatment approach is called cognitive-behavioral therapy, or CBT, and it involves the following.
A thorough physical exam will rule out actual medical problems. You will review this information (one time only) and then accept it as evidence of good health.
Education about bodily symptoms is a vital. You will be provided with nonthreatening explanations for the bodily sensations that you frequently misinterpret as threatening symptoms of underlying diseases.
This is not the same as providing reassurance. You must use this knowledge yourself, rather than asking the doctor for the same information many times.
Cognitive therapy techniques help modify unrealistic interpretations of harmless physical sensations. A therapist helps you explore the evidence for and against the threatening misinterpretation.
Exposure Therapy and Response Prevention
Jonathan Abramowitz, PhD, is a licensed clinical psychologist and leading authority who specializes in the treatment of obsessive-compulsive disorder and other anxiety disorders. He is also a professor of psychology and the director of the Anxiety and Stress Disorders Clinic at the University of North Carolina at Chapel Hill. 
Listen to a podcast on health anxiety. 
Psychological Treatment of Health Anxiety and Hypochondriasis: A Biopsychosocial Approach,  by Jonathan S. Abramowitz and Autumn E. Braddock (Hogrefe Publishing, 2008)
It’s Not All in Your Head: How Worrying About Your Health Could Be Making You Sick,  by Gordon J.G. Asmundson and Steven Taylor (Guilford Press, 2005)