Sounds like you have an unstable (instable?? sorry my brain isn't working well!) pelvis. Your ligaments and things that hold it all together are probably starting to relax more and loosen with the hormones in your body. I get almost the exact same thing and the doctor has suggested I have SPD and my sciatica and have done so since fairly early on, about 22ish wks. You can go to a chiro, I have heard they can be really good at adjusting things. You can get support belts to help your pelvis stay int he right position. When you roll over in bed try to keep your knees together and roll your body all at once. Accupuncture can help, but make sure if you go to someone like a chiro or accupuncture the have experience in treating pg women. Avoid pushing through any pain. If something hurts, if possible don't do it. Avoid heavy lifting or pushing. Supermarket trolleys can often make your pain worse, I can't push DS int he pram anymore either, he's just too heavy, though it was a good opportunity to teach him how to walk with me! Pelvic floor exercises can help.
Sorry you're going through this. As if the pains and discomfort of late pg aren't enough, this just takes the cake doesn't it???