There is a new doctor in your town. His office is open 24 hours a day, seven days a week. He is a specialist in every disease. He never turns a patient away. And his service is completely free.

Got you excited, have I? What’s his name and address? Well, his name is Dr Google and he’s as close as your nearest computer.

There is a massive exodus from the medical sector to the Internet, the media reported recently. Why queue up for hours in a waiting room full of grotty, diseased neighbours to spend a fortune for a diagnosis by a single person?

Simply type your ailment into the Google search engine or Yahoo Answers and then wait for responses to come pouring in from the Hive Mind.

I had this in the back of my head somewhere when I went for my usual weekend run with my banker friends. Halfway to the starting point, I heard a strange ticking noise.

I looked everywhere for the source. Since I had stripped to shorts and a singlet, I didn’t have much to search. The ticking, strangely, was coming from INSIDE my right leg. I thought I might be going crazy but the other joggers could hear it too.

This was a case for Dr Google! When I got home, I typed "help! my leg is ticking!" into the search engine. I then sat back to let the power of the Internet do its magic.

"You have a damaged meniscus," one response said. I have no idea what a meniscus is, but I felt the answer somehow insulted my manhood.

"You have a posterior cruciate ligament injury," said another. This was worrying for two reasons: one, I didn’t understand any of it, and two, it mentioned my posterior, which, as far as I know, is a euphemism for "bottom", or am I thinking of "posterity"?

Other answers seemed to come from amateurs. 1. "You have a screw lose in your leg, or more likely, your head." 2. "You are bionic and your parents never told you." 3. "You ate a clock in your sleep." 4. "You are a replicant and Deckard is on his way to wipe you out." (A reference to the movie Blade Runner.) 5. "Al Qaeda terrorists have hidden a time bomb in your right knee."

By this stage, I was about to give up, when the next page of Google fetched up a conversation on a medical website. Veronica, a young aerobics teacher, said: "Two days ago after the gym I noticed my left knee making a click sound whenever I went up the stairs. Should I be concerned?"

A doctor replied: "Dear Veronica, the vast majority of clicks are completely harmless." He told her that if there was no other problem, such as pain or swelling, the noise could be ignored.

So I ignored the problem and signed up for another run. The information was right. The ticking had no effect. Dr Google had scored.

I mentioned this to a doctor friend. He listened to my knee. "Dr Google gave you a choice of diagnoses, but you chose the wrong one," he said. "I go for the loose screw theory."