Something similar happened to me last weekend! I was almost 12 weeks pregnant and my lower abdomen on my right side, lower back and upper right thigh were in pain. It lasted through the night, woke me up at 3am, I had to take more tylenol to go back to sleep. My doctor thinks I may have actually had a kidney stone! Sounds like your pain is on both sides so probably not what I had but it can just be your uterus/body stretching. Either way TELL YOUR DOC! they may want to culture your urine just to check and make sure you don't have an infection! hope you feel better soon!
I would lay down on your left side for about an hour and drink a large glass of water. If the pain subsides then I wouldnt worry but you should call your OB and make them aware of the situation. Back pain can be normal in early pregnancy. As long as the pain is not accompanied with bleeding or spotting and goes away it should be alright but your OB may want to check you to be sure, good luck to you.