Back pain?

Malarie • 26 years old, Married, Mother of a 7 yr old girl & newborn boy!
Hello all! I am going to be 18 weeks tomorrow and have been having bad back pain lately. I'm a bit surprised cause I'm not even that big yet & didn't expect to have back pain this soon although I was in a car accident a few years ago & it affected my back greatly. Are any of you experiencing back pain this early?