I had severe back pain throughout both my pregnancies. I was told it was due to an old back injury when I was a teen, but I understand that some back pain is quite normal during the second trimester, the uterus is pushing up against something. Funny, as the baby got larger the pain subsided. You would have thought it would be the opposite. Maybe the baby was in a better position. I had forgotten about the old injury until I got pregnant. Sometymes the pain was so intense I had to hold onto the counter. Thank god I don,t have it today. I would still see your GP, save the worry.