Thanks Headdoc.
I got some pain meds already (paracetamol), and am feeling better. It's interesting that you mentioned traditional weight lifting and how it won't protect one from this type of injury/sprain. I've mostly done nothing but traditional weight lifting, and of course cardio and other sports recreationally when I have the time (basketball, rock climbing etc), so I reckon I could certainly benefit from some core strengthening exercises.
In any event, I feel better already. The pain has subsided greatly, though it is still there (I've managed to pinpoint it to my spinal erectors). I'm taking a week off of the weights, upping my magnesium intake, doing light stretching and trying not to strain myself. I think I'll be fine, but I will definitely incorporate some pilates/yoga type core training when I resume lifting. Obviously my midsection isn't in the best shape, and doing traditional crunches, with or withought weights, isn't cutting it.