I hope your sore back gets better, soon. I've had the same issue in recent days. I don't think my new sit-up regiment is agreeable to my lower back. I did some tossing and turning in bed this weekend trying to find a pain free position to sleep in. I had back issues for 20+ years and the walking & weight loss seemed to take care of it. However, the problem did get worse before it got better - so I'm hoping that my body will adjust to the new exercises in much the same way. I do need to strengthen my core muscles.

Again - get well soon. Pain, pain - go away.