I had pelvic instability with my first two pregnancies and saw a physio. Apart from strapping my back and suggesting a belt, it didn't really help much. With our third pregnancy our doula recommended a chiro who was fantastic. She really worked on aligning the pelvis as I'd always have pain on one side. I could actually walk really well during third trimester, which is something that i struggled with for the first two pregnancies. I've since recommended a few other friends who have experienced something similar when pregnant and they have also raved about her. I'd previously never seen a chiro before, but would highly recommend one now. I even got my DH to see her and he feels it makes a big difference for his neck and back.