Lower back pain

Monica
I've been having constant lower back pain for over 24 hours now. I'm 7 weeks 1 day. I freaked since my miscarriage in July started with lower back pain so I went to have a ultrasound. Baby measured 7 weeks 1 day with a heartbeat of 148. Nurse said everything was great but didn't have any answers as to why I'm having the back pain. Anyone else had this? How long did it last? I'm so uncomfortable!