A.,
I experienced the same problem during my pregnancy. Just before heading to Washington, D.C. for a weeklong seminar, I finally broke down and went to a physical therapist. She taught me several different exercises that helped ease the pain within a couple of days (I know that may not sound as quick as you might hope, but to me, it was super speedy after suffering for weeks and traveling to D.C. in that condition!).
I cannot remember the specifics of the exercises but will try to share what I can:
1. Lie on back with legs bent; pull right leg up, placing the ankle on the left leg knee; push on the right knee to stretch; hold for 5 seconds; repeat 10-15 times and then switch legs
2. Cat spine (pilates): While on hands and knees, arch spine toward the ceiling, hold for 3-5 seconds; then pull abdomen down, stretching the back in the opposite direction; repeat 10-15 times
3. Lie on back, knees bent/feet on floor; pull the right knee up the chest, pushing toward the left side of the chest; hold for 5 seconds; repeat 10-15 times; repeat with the left leg.
Unfortunately, that is all that I can recall. I think there were another two or three exercises, but I just can't remember what they were. Hope these help! If you have any questions (directions are not my specialty), don't hesitate to ask!
R.