back pain

Any other July moms having lower back pain. My lower back is killing me.  I have dull aches but when I sit or stand up it becomes a sharp pain. When I went to l & d last week they did a swab and said that It wasn't showing me due in 2 weeks.  I don't know if I should rely on the swab. I have only gain 7 lbs during my pregnancy. Due in 4 weeks. And the dull aches and pains are coming from mostly my left side. Just wondering????? Please share your experiences.