The gist: from about 4:00 - 7:00 yesterday, she was having real balance issues. Kavi would try to walk, and fall down every few steps. Aside from that she was totally happy and normal, and by the time the doctor saw us around 8 p.m., the problem had disappeared completely and she was walking just fine (allowing for tiredness from being long past her bedtime). The lack of symptoms made it much harder to diagnose the underlying problem. So the doctor said it may be nothing, it may be something, watch her for the next week and keep a log of any further balance issues to take to your pediatrician. So that's where we are.
When I tried to research balance issues on the web, it came up with something like 600 different diseases/conditions/etc. that all have trouble walking as a symptom. So that was useless.
What's particularly frustrating right now is that we'd been almost certain that it was just a result of an ear infection. We all had a cold last week, and kids often get ear infections after that, which can leave fluid in the ears and affect balance. It would have been the simple explanation. But the one thing we learned from our three hours in the E.R. (which Kavi was a trooper for, thank god), is that her ears look great. Totally fine. So that's apparently not the issue. (Now I'm trying to figure out whether it's possible that it's infected without any obvious redness or other symptoms. Web is not yet helpful on this.)
This is scary, folks. The doctor threw around phrases like 'possible neurological issues'. We do not like possible neurological issues, no we don't. We want them to stay far, far away from our child. Hopefully it's nothing. We'll watch her and see.
The other good thing we learned is that Children's Memorial seems like a pretty good and competent hospital, even if there's a long wait in their E.R. for non-urgent cases. Their E.R. has crayons and toys and books and a playhouse; I think Kavi thought we had gone to a playspace instead of a hospital. We're going to try to find a new pediatrician associated with them, because we really do not love our current pediatrician. If you happen to have any recommendations for one (that takes HMO insurance), please do let me know.
7:50 update: She just got up, and is definitely a little wobbly walking -- not actually falling, but keeps reaching out to catch herself on things. Dammit.
8:30: Spent a while on the couch watching Sesame Street, and now seems to be walking fine.