I have the same problem too... I've been having pelvic pain since 1-2 weeks ago..
After hearing some recommendations here and from my friends, I attended prenatal yoga classes.. it doesn't directly solve the problem, but each time b4 class starts, the teacher will ask everyone to talk about our own pregnancy pains for her to understand and guide us thru... every class that i go to, around one-third to half will have this pelvic issue from approx 30 weeks onwards as bb gets heavier... its a common pregnancy pain..
In my case, walking too much will cause more pain. However, if I limit my walking the pain is very manageable...