Thanks for the suggestions, ladies! Now that it has happened once, I'll try to be more conscientious, but usually I am really in tune with my body.
Before pregnancy I tended to have pretty low bp, experiencing the wooziness when standing on occasion, so that might be it, although I haven't really had that wooziness while pregnant, and my bp hasn't been significantly lower at my appointments. This happened at the end of the shopping trip, on my way to the car, intime0, and I really think that the jumpy cart on the cobblestone was the trigger, which is why I was thinking something like vertigo.
I have been drinking tons of water lately, ithappened, especially when working at home and at night. At work I drank about 40 oz of water from noon-6pm, but nothing for the 45 minutes before the incident. Your incident sounds really scary and I'm glad it hasn't happened again. I did not feel nausea with this, though.
NewMumJoy, now that you mention your experience, I have also noticed that I can feel the blood rushing/pulsing in my head (and gums, and belly) and I also attribute it to the increased blood volume, but I don't recall experiencing it lying down.
So glad you had a great checkup, LilyTiger! Sounds like you have an amazing doc. I have been worrying a bit about lead myself. Everything was newly painted in here, some new walls, etc. when we bought the house in 2009, but in a few of the rooms they used a weird paint on the old baseboard molding that has been peeling (although it is not removing the paint below it). We need to get that checked. In other parts of the house they installed new molding, so it's not a problem everywhere, at least.
On that note, I am wondering what the consensus is here on building up savings vs. home improvements. We are pretty comfortable with the updates that the former owners have made and could probably live in the house as is for a long time, although we need to do small maintenance work here and there. The former owners left a good deal of the bamboo flooring they had installed in the living room and other areas, and I really want to install it in our bedroom (the bedrooms are carpeted), but dh is not really responding to my hints to do that ourselves--he'd rather hire someone. Another project that we've been considering, this would be the most expensive, is upgrading our fence and installing an automatic gate for the driveway. We've had a slight uptick in crime around here (mostly opportunistic--someone stole dh's truck's spare tire, which was surprisingly expensive to replace, break-ins to houses in the area being remodeled by flippers, the worst being a break-in through the garage and the homeowner had not turned on her alarm, so they pretty much cleaned her out) and we have been thinking that the fence across the driveway (leading to our garage entry) would be good for dh to park and be a further crime deterrent. But, another part of me really wants to keep building up our savings and doing routine maintenance only until we know how the baby and, especially, childcare will affect our finances.