Hi, KDD . . . I find that by sharing and answering the questions that I am able to on these boards, I can momentarily come out of my own health worries and look at someone else's. I am fortunate in that I have inherited some medical encyclopedias, prescription books and alternative medicine books from my Dad.
I also have a lot of personal experience with real health issues I have but thankfully none of them are life threatening (IBS, osteoarthritis, sciatica, low grade asthma, hypoglycemia, to name a few). One thing about being extremely aware of your body is how you can make connections to symptoms that seem horrible but are quite explainable when you can look at yourself via the whole picture.
A lot of these internet diagnostic web sites do not state how rare or unlikely some of these things are that they are giving symptoms for and they also do not look at the whole picture like past medical history, family history, location, etc. When you are looking at these sites, you need to ask yourself how likely is it that you have it? Would this be something that would have shown up at a last doctor visit? This can put your mind at rest a bit.
A lot of doctors also have E-Mail service. You can always see if yours does and if you find yourself in a health anxiety situation, E-Mail or call your doctor to see if you need to come in. This and a good night of sleep would probably be better for you than staying up and doing searches.