I'm pretty sure this was my subconscious trying to tell me something, but I have no idea what.
Went to the allergy specialist today: was already worn out before I got there. Had to go into work. Thought I was going to slip under the table during a meeting; got more mumbly and incoherent and bad; then thought I was going to faint on the platform while waiting for the tube. Spent the evening almost entirely on the couch at home; had dinner cooked for me.
My lesson: need to eliminate the rest of the stress from my life so I can get better. With luck this will be over by the end of February. I can't believe how everything in my life seems to have turned upside down since this started, how I've got a much closer view of who my friends are and whose just there for the good times. And, as ever, how people say, "Oh gosh, if only I knew you weren't doing well I would have been there to help" but then it turns out that people actually don't want to do that if you need help for more than a few days. I think I'll have bid goodbye to a lot of friends since this illness started; but as many people have said, in fact I've really just become much clearer about who my real friends are.
Now to spend a minimum of a month mostly at home keeping quiet and trying to get well in a nice, supportive atmosphere. I think I can do it. I just need to be patient.