Belle, I have been getting pelvic pain for a while now and it has become more painful the last couple of weeks. I first noticed it around 20wks and it's caused by the relaxin hormone loosening up all those tendons and your pelvis moving more than normal. I saw the physio for the first time today and she said it's worse when you have one loose side and one side that's more stiff which is what I have.
It's always worse when I've been busy and on my feet alot, but it hurts mostly getting in and out of bed, getting dressed, walking up stairs, going from sitting to standing. The physio taped me up to try and get me some relief, and said I have to try and change the way I get out of bed/car etc by keeping knees together, walk up stairs by taking one step at a time. It takes ages but it seems to make a difference. If this fails I will end up getting a belly belt for some extra support.

So, it seems that what you are experiencing is completely normal and well worth seeing a physio for a bit of extra help. I just called the physio dept at the hospital I am booked in to and it cost me $15.