I have ruled out thermometer error.
See, I figured thermometer error could be a very distinct possibility because the one I was using has the battery it came with; who know how fresh that is? Also, the box it was in says "not for human use."
Yes, I got it out of my canine first aid kit. What? I've never used it on an animal and I dipped it in alcohol before the first time I used it!
And yeah, I don't have any dogs, so what am I doing with a doggie first aid kit? It was cheap at the employee sale last year! It's got all the same stuff that would be useful in a human one, it's just all labeled not for humans. So I keep it in the trunk of the car. I figure if I ever need it in an emergency a non-human bandage, splint, etc. is better than nothing!
So I dug around by the bed for the "human" thermometer (which is almost identical!) It has a brand new battery but I hadn't been using it because Lump aparently decided the garbage can was a good place to store it, and I hadn't been arsed to look for it before now. Anyway, I took my temp with both thermometers at the same time and they both came back 99.5º. So, I have a fever. Hmmph. Don't want a fever!
But at least I don't have a weird doggie fever!