I'm dying. I'm convinced of it. The evidence is simply overwhelming.
Take last week, for example: On Tuesday I woke with a headache, the second in two months.
The doctor told me to take an aspirin, but what if it's a brain haemorrhage?
A few minutes on the internet was all it took to convince me my head could be playing host to a tumour the size of a football. And if I am haemorrhaging that could explain the problems I been having with my eyesight.
The small print in the newspaper is now so small it has started to look like bacteria. At the rate I'm going I'll be lucky to make it to retirement without a guide dog and a white stick.
I'll admit there are times I feel fine. But even if I'm bouncing around like the March Hare in Alice in Wonderland I'm not only convinced my body is plotting against me, but that some exotic new strain of the E.coli virus is hard at work making a home for itself in my bloodstream.
Having lulled me into a false sense of security, in due course it will cause my vital organs to shut down and my innards implode and before I know it I'll be communicating with a roll of the eyes and taking my meals through a plastic tube.
Such fears are irrational I know that.
Yet in the last few years alone I've had CAT scans and colonoscopies, MRIs and ECGs, chest X-rays and sleep studies, turbine and tonsillectomies, and paid so many visits to my GP that he once joked about inviting me to the office party.
I've sought the advice of neurologists, ophthalmologists, dermatologists, rheumatologists, podiatrists, pulmonary surgeons, Ear, Nose and Throat experts, acupuncturists, chiropractors, hypnotists and holistic healers and on top of that I've even been to Lourdes!
And every specialist consultation involved that nerve-wracking moment when they shut the door, plucked the test results from the file, and uttered those five truly terrifying words: "There is nothing wrong with you."
Because the one thing a hypochondriac can't bear to hear it's that he's fit and well.
And if there is one thing more irritating that that, it is when your bodily fluids instead of underperforming start to steal the show eliciting gasps of admiration for everything from the colour of the urine to the consistency of the stools, which is what happened to me.
Yet instead of proving a source of comfort, it made me more convinced the medics had missed something.
So it came as a considerable relief to hear about a company that could take a small sample of your saliva and use it to assess your risk of getting any one of nearly 100 different diseases.
With almost feverish excitement I gathered my saliva sample and cheque and sent them off to the lab and started pacing up and down. Then a few days ago up popped an email with the results.
Of the wide variety of diseases they test for it is clearly the scary stuff that people are most drawn to, the results for the big two - Alzheimer's and Parkinson's disease - were locked away behind several pages of explanation and qualification and even required their own password.
I felt my heart beat a little faster as I clicked on the first one: Parkinson's.
My results were normal and my chances of getting it pretty much average. Then I clicked the other box and felt the blood drain out of my face.
The gene most closely associated with Alzheimer's Disease is known as APOE. There are three varieties of the APOE gene, each carrying a different level of risk, and I have the one that carries the greatest risk of all.
Scanning the notes in a state of low-grade panic I discovered that things could have been worse. It seems those luckless enough to inherit that type of gene from both their mother AND their father stand an even greater chance of getting the disease then I do.
There are those who question whether these sorts of tests should be available to the neurotic and the highly strung - people like me, in other words.
But I found the results allayed more concerns than they generated.
It is by no means certain that I will get Alzheimer's of course, but I can at least keep tabs on my blood pressure and cholesterol - two factors which are known to have a bearing on the disease.
And of course I have the perfect response the next time I come across one of those smug specialists. To borrow a phrase from the gravestone of the comedian Spike Milligan: "I told you I was ill."