A friend of mine, also a mum, had been having terrible problems with her back recently. It was so bad for about a week that she couldn't even look after her own 19-month old son. She's able to stagger about now, but apparently it's going to be 4-5 months before she's "better".
All my life I never had back pain. I could do high-impact aerobics without shoes on and not get shinsplints, and I could use my back like a crane and never experience a single twinge of discomfort. I'd always put this down to being short, because most people I knew with dodgy backs were tall.
Lately though, it seems that every time I put my back under any sort of strain whatsoever (getting the buggy around the narrow porch, over the step and through the front door is a prime asking-for-it example), my back responds with acute pain and sometimes the inability to move easily for several minutes at a time. In the evenings, the boy gets his massage thumbs out and finds knots the size of golfballs on either side of my spine.
Perhaps, in my old age, my body is finally paying me back for all those times I pogoed in my extraordinarily heavy Doc Martin shoes.