Hayfever.
Within a day of arriving in Berlin I re-developed hayfever.
A major sufferer of this in my teens, it faded away when I moved to London but returned with a sudden vengeance here.
I can't take antihistamines. So I'm lumbered with streaming, unbearably itchy eyes as a main symptom and sneezing as a close secondary problem.
I take a little comfort in the fact that it is transitory.
But it's not nice.