I went out to walk this morning. I don't know why, but I started running, even though I am definitely sick, with a sinus thing that is going to require a trip to the doctor, after a week. So, I felt like crap, but it had nothing to do with running!
I ended up running for about a mile and a quarter and then walked back up the hill for another mile.
Now I know why I felt so awful after my ride on Wednesday. Duh. I'm sick.