There is a fine line between watching your health closely for any symptoms that might indicate an illness and hypochondria. If you ask most people who get a headache or other ailment, they often think that there is something underlying which may be serious, even though they know in their head that it is just a regular part of life, and is caused by stress or eye strain.
A slight pain in the chest can have you scrambling through the internet seeing what might have caused it, and a tooth ache can send you looking through the cosmetic dentistry guide to try to find out what is wrong with you.
It tends to be worse if you have the history of a particular illness in the family as you are convinced that any symptom might be related and that you are likely to suffer the same fate as one of your relatives.
This fear is especially powerful if your relative has suffered greatly from the illness and you are forever checking yourself and stressing over something that just may never happen.
GPs are generally quite tolerant, especially if you have a family history of illness, but their patience does wear thin if you turn up at the surgery telling the doctor what is wrong with you and asking for a particular type of medication! Many GPs get very frustrated at this self-analysis and often send the patient packing.

communicate-health.org.uk - Specialists in talking about your health.