I found out I'm expecting baby no.3 last week and since then I've experienced quite severe lower back pain. Best way to describe it is like a burning ball of pain in my lower back. It's worse when I'm sitting down for long periods (e.g. I work from home on PC). Don't want to be taking lots of paracetamol or I'd be on it constantly! I'm wondering if anyone has experienced this and is it anything to worry about. My last two pregnancies were pretty pain-free except for the 'stretching ligament' type pains.