Here's the line that struck me:
Returned to work in November/December
Disappeared in January.
I'm not surprised. The brain is more sensitive than we know. In March 2012 my husband had a benign meningioma removed from the lining of his brain (the meninges). He was back at work by the middle of April, but began to get insomnia and many other symptoms so that by August he could barely function. Luckily, through some combination of drugs and the brain repairing itself and who knows what else, he got through it. Was the hypothalamus, and left temporal lobe "tickled" during the surgery. Maybe.