Where did the oxygen go?

Greg and I parted ways in the morning, and I had a long day ahead of me, since I spent the night in Eads. I was dead set to get to Limon, which I realized later was over 1000 ft higher than Eads. And 80+ miles away. Yeah, that was interesting.
At Kit Carson, CO, I ran into a guy named David who was biking across the US, and this guy was intense! He was from Malaysia, 59 years old with a wife and 8 children (all grown) back in Asia! Crazy! He had retired from his job several years ago, and has taken something like 4 bike tours since then, all over Asia and Europe, and now the USA. Super cool guy. Check out his website: www.bicycletouringmalaysia.com
I pedaled on through Hugo, some crazy road construction, miles without anything, and finally made it to Limon. I got there after sundown, and I couldn't find a place to stay. No one in town suggested staying at the park, as the police would certainly accost me. I went to several stores and gas stations, and no one had any suggestions, except the KOA in town. I called them, and they charged 30 bucks for a tent camper. I mean, c'mon. Thirty bucks? And all I use is the bathroom. So I sat outside the gas station for several hours, trying to figure something out. 9 PM rolled around, and I had nothing, and I was starting to get really worried, not really sure where the heck I was going to stay. Too late to go knocking on peoples doors, to see if they would let me stay there, and the police and fire stations where shut down for the night, and I was running out of options pretty quick. Thankfully, though, a police officer pulled up after a while, and he was totally sympathetic to a travelling cyclist. He calls up a coworker, and finds out that there's a fishing pond a couple blocks away to stay at where I wouldn't be bothered. Huge relief! And only a few blocks away, as opposed to biking for another 5 miles! Thanks God!
After I set up camp, and right as I finished eating dinner, right when I though things were going pretty well, something attacked my stomach. Horrible feeling! I'm thinking that it was altitude sickness, or maybe that I didn't cook my corned beef hash well enough, or something. But until I passed out in my tent at around midnight that night, I was rolling around on the ground, half-conscious, wondering what was going on. Thankfully, I slept it off, but I still don't know what it was. Worst night of the trip, hands down.