Whatever hossy you are at, get a referral to physio and get yourself a pelvic belt (duno if they have a proper name). I had really bad tailbone pain (due to weak pelvic floor muscles apparently?) and uneven hip placement and that belt really helped. Took a bit of getting used to for me and bub (he used to kick something shocking with it on), but it really helped when i was up and moving (standing at work, walking around shops and doing housework). I had the pain from 15weeks and it continued when i wasn't pregnant not quite as bad though. I'm expecting it to flair up really quickly soon. If you can afford it find a chiropractor that deals with pregnant ladies might be some help. I'd love to go see one, but alas funding is limited. I think they work wonders!
There is something called Pubic Symphasis Disorder or something like that....might be more similar to what you have. I think there is a forum on it somewhere here.
All the best xx... There's not really a whole lot you can do about it i'm sorry.