I assumed -- in fact, we all assumed -- that Phil's continual complaints of "the flu" were either psychological or faked. He would become ill and fail to fulfill promises while he lay in bed for two or three days at a time. Guests would have to leave, and he would break promises and appointments.
Well, from the symptoms, which I will not describe in detail because some of them are disgusting, I am certain that he was suffering from a congenital gall bladder problem that our adult son also has. The diarrhea, the fatigue and other symptoms all cry out. And our son, just as his father did, suffered an acute attack of non-alcoholic pancreatitis. Phil always thought that his attack had been caused by drugs, but our son does not use drugs. In fact, he's a health nut and a licensed nutritionist.
After nearly dying, and then spending thousands of dollars on medical tests, Christopher learned that his gall bladder has a congenital defect, and that is why he suffers period bouts of "the flu". He is forced to send guests home, break appointments and lie in bed for two or three days at a time. Since he inherited this problem, and I do not seem to have it, he must have gotten it from his father.
So, Phil, I am very sorry for doubting that you really were ill.
~~ Tessa Dick
PS: My memoir, Firebright: Remembering Philip K. Dick will be available at Amazon dot com in a few weeks.