Hi,

back aches in early pg is quite normal. I had them for a few months, I can't remember when they actually stopped. I used to sit with a heat pack on or at least put the heat pack at the bottom of my chair so the heat would move upwards to my back, I didn't leave it on for too long as I was unsure if the heat was safe. I found they were worse when I was sitting on my computer chair and actually bought a cushion (like the ones for your dining chairs) for it, which did help a little.