My back has been hurting soooo bad. I see the chiropractor, but lets face it, there's only so much he can do. Apparently, I've a good bit of inflammation too. That's not helping. Anyway... Pelvic rocks have been a life saver! I'm talking instant relieve that lasts a while. Oh. my. goodness! So glad I learned about these things. Here's a link in case someone else needs to know what they are. http://www.birthingnaturally.net/exercise/preg/pelvicrock.html  Doing some other stretches helps too, but this one is the one that fixes it imediately.
A second thing is, I swapped my office chair for my birth/stability/exercise ball. So much less pressure on back.
Anyway, thought I'd pass that along in case anyone else is having this. I'm almost in tears at times if I sit too long or stand too long. I made the kids breakfast burritos for the week last night and after doing that, my back was terrible! I decided to call them Back Breaker Burritos. :-)