Or maybe it was just a Monday?

Yesterday evening was horrible. I came home and went to bed with a stomach and head-ache. I crawled out of bed by eight and got enough energy by nine to reheat some stale leftovers before I went back. Sleep eluded me for most of the night because the stupid headache wouldn’t go away.
Today I feel better. A Tylenol in the morning helped.
Now I have to wonder why I was feeling so bad. When you are awake in the middle of the night, your brain tries to find things to do, and random theorizing is as good a task as any.
The most popular: I was cramped up in a rainy house ever since the long run. Yesterday I walked forty minutes to a training session downtown. This exercise might have finally caught up all the abuse I did to my body. This caused the utter collapse of my health leading to my sickness.
Another theory: I went out to lunch at the Mongolie Grill and possibly spent too much time scraping out the dregs of their rice noodle container. I don’t know how long they had been there, and they may have gone bad.
Final theory: The classroom got stuffy and hard to breath. It was crowded.