I'm 7 weeks 1 day and have been having constant burning lower back pain for over 24 hours. I freaked since this is how my miscarriage started in July. I went to have an ultrasound and baby measured 7 weeks 1 day with a heart rate of 148. Nurse said everything was great but didn't have a reason why I'm experiencing the back pain. Anyone else have this? How long did it last?