I thought about altitude sickness as well but I honestly don't believe that was the cause. The doc at the hospital did sputum, blood, and other tests and came to the conclusion it was some sort of bacteriological infection. My own doctor agreed when I got home. Add to that the fact that I've been playing in the same mountains for over 30 years and have never had even a hint of trouble. I think I may have inhaled something in the road dust while riding my ATV up to the trailhead early in the trip. Lots of sheep grazing up in that area in the summer. At least it wasn't anthrax...

You are absolutely right about being cautious. I'm going to be especially careful the next few times out.