The Internet is a wonderful thing, but it should not replace the advice of a trained health provider. While the Internet makes it easy to research symptoms, treatments, prevention and general information about a condition, the Internet is unable to fill the role of your health provider in treating your specific condition. Also, search engines like Yahoo and Google might not always turn up the most reputable sites for information.
For information on what look for when evaluating Internet resources, visit http://www.extension.org/pages/Health_Information_on_the_Internet.