As I said previously, as soon as I moved back indoors from my 5 1/2 month long hike, I started feeling terrible. All the health problems I had prior to my hike (and I had been attributing to stress from working too many hours at my former job) were back within 5 days.
Just to see if it would make a difference, I pulled my sleeping bag back out and slept outside on the back deck for a couple days. After sleeping outside, I would wake up fully rested, no headache, and with clear sinuses. That clinched it. The house was making me sick!
So I sat down and brainstormed. The worst part of the day was upon waking... so the bedroom was definitely suspect. I tried closing the vent to the central air and opening the window before I went to bed -- the headaches and sinuses were definitely lessened, but not as good as when I slept outside. The other room where my symptoms were at their worst was the bathroom. Whenever I went in to shower or brush my teeth, I would get watery eyes, start sneezing, and start to feel nauseous and headachy. Not to mention, the smell of the cleaners!
I reasoned that I was reacting to one (or all) of four things: (1) dust, (2) the air quality in the house, (3) the bathroom cleaners, and (4) possibly the toothpaste? That's seemed like more of a stretch, but it was a consistent with my bathroom trips. And I set out to learn as much as I could about these things.