This is the only post I am going to make on this subject. I do not want to be one of these people obsessed with their physical problems. They are best forgotten whenever one can!!
After some months of discomfort with an extraordinarily dry mouth that wasn't cured by drinking water, and scratchy eyes that felt as if I had something in them (if you've ever had conjunctivitis, you might know the feeling), I went to have a proper check up. This included a thorough eye test which included looking at tear production (which was abnormally low) and blood studies (which were normal) and a biopsy of my saliva glands (also normal).
Because of my symptoms -- and other side problems (osteoarthritis and pain, weakness, problems with concentration and focus, which may or may not be related) -- the specialist decided it was probably Sjogren's Syndrome, which is an auto-immune disease. You can read a summary about it here, if you wish. It is incurable, but not usually fatal unless you are really, really unlucky. It can make life pretty miserable, or be fairly mild in its symptoms. At the moment, the latter is where I am at right now, although I don't think I could survive without eyedrops. In fact, not using them would probably lead to corneal scarring. I am on a drug which I hope might improve other symptoms, especially the saliva problem. (If that gets really bad, it can affect speech and digestion).
Given all the kinds of things that can happen to someone of my age, this is really not so bad. In fact I feel I'm very very lucky when I read of people so much younger becoming ill with more serious autoimmune diseases or unpleasant things like cancer.
I don't expect it to make much difference to my life at this stage. I may write a little slower, but I think I can still manage one book a year. I shall still be doing all the other things that I've been doing in the past, like attending conventions, travelling, etc. Fatigue does make me a little slower at most things, but then that probably goes for most people as they grow older anyway.
Generally, then, I'm determined to stay fit and not to let this wretched syndrome dominate my life.