SK,When you're in the grip of health anxiety, it can be terrifying. It affects all aspects of your life – your work, your relationships – because you can't think about anything else, and you're living with this expectation of impending death.
Everyone looks up their symptoms, but the internet tells you everything and nothing. Type in flu symptoms and you will be able to find a huge range of diseases from a common cold to the early stages of an HIV infection.
Cognitive behavioral therapy (CBT), which aims to change thought patterns and behavior, can reduce the symptoms of health anxiety.
One CBT technique involves getting patients who believe their headaches are a sign of a brain tumor to create a pie chart where they imagine all the people who woke up that day with a headache, and list the causes for it according to probability: dehydration, a cold, migraine, tiredness, too much caffeine.
Check out this link and perhaps work through some of the modules - it is an interesting and helpful resource.
http://www.cci.health.wa.gov.au/resources/infopax.cfm?Info_id=53