Well, she started perking up and sleeping better, but then a rash appeared. I wasn't too worried at first, she didn't seem unhappy, so we carried on with our plans. (Magnus' grad reunion) By the time we were getting ready to leave the rash was pretty bad, so we stopped in at a clinic. The diagnosis: Roseola Infantum. It's basically 3 days of a fever, often quite high, followed by a rash as the baby feels better. No complications to speak of, you just have to let it run it's course. The rash looks bad, but she doesn't seem to mind it.
(It doesn't show up well here, but you can see it a bit. It went from in the diaper all up over her face!)
I'm so happy she's feeling better, it's great to have my happy baby back!