It's just because we still haven't completely evolved to an upright position. It could be a muscle spasm, a sprain of a muscle or ligament, or a joint or disc injury. There's a National Institutes of Health study that says that chiropractors are more effective than traditional medicine for low back pain. Usually the pain gets better with a couple of days of anti-inflammatories, ice and rest.

(edited because I haven't completely evolved to typing)

Is this because I'm not really young anymore? Or because I need to lose 30 lbs.? Both? Neither?

What everyone said about not getting Annabel up. If she wakes and is inconsolable before Dylan gets home, let her eat cookies in her crib. She'll perk right up. Dylan can change the sheet when he gets home.

And it's normal to just be on one side like this?

When my back goes out, it normally goes out just one one side below the hip.

So DH is going to have to use a bunch of his sick time or work from home until this is better, huh?

And it's normal to just be on one side like this?

Yep.

DH just got home, and AB just woke up--perfect timing, at least.

I think it can be. Sciatica certainly is. And my neck pain is one sided. You probably carry the baby on one hip, and when she's in her car seat, you probably carry her on one side. Even if it's the other side, it might irritate this side that's hurting. This could be related to your fall, or not. I don't think muscle spasms have to be centered, or symmetrical, or anything.

Did you take anything yet? If not, take 4 (that is 800 mg) Advil/Motrin/Ibuprofen with a glass of milk, and something to eat (cookies, bread, something solid).

Oh, yay for husbands who can get home quickly!

Doctor's office called back. My initial message apparently didn't do a good job explaining what had happened and how bad it was, because now they're going to grab my nurse practitioner once she's out of her current appointment and call me back.