I too have really bad back ache and I hate it lol. I think it might be a mixture of bad posture and relaxin hormone as well as lax muscles from having the other babies lol. I will look at seeing my osteo very soon to try and loosen them up and also start some exercises to strengthen the core muscles. I can't stand the thought of going nearly the next 20 weeks with this pain either.

Good luck with yours

Kim