I have found it.
This morning when I woke up sneezing and bleary, I knew what the problem was. The reason for the week long headache. It's not a snake-like parasite, wrapped around my brain, like I know most of you were thinking.
It's the same thing that has been giving me much delight, lately. Cherry blossoms... sunshine... flower scents on the wind.
It is the advent of Spring. Allergies. Sheesh. From this time forth, you will be lucky to get anything whatsoever out of my brain. And now I am going to drink a gallon of my pregnancy tea, because it is full of nettles, and nettles help.