Sorry to hear about the pain.  I had really bad pain that came from my sacroillial joint; it lasted from about 28 - 33 weeks.  I saw a physiotherapist, who gave me exercises to do, and she also taped my back to give the joint extra support.  I also used a Medella maternity support belt around the same time.  I'm not sure which it was, or if it was both combined, or if the baby just shifted her position in me, but shortly afterwards, the pain was gone, and the rest of the pregnancy was comfortable  (so there is hope !).  Best of luck !