Your problem sounds exactly like mine when I was 9 months pregnant, that happened to be "pelvic pain".
Here is extract from the site linked below: "Any activity that involves lifting one leg at a time or parting the legs tends to be particularly painful. Lifting the leg to put on clothes, getting out of a car, bending over, sitting down or getting up, walking up stairs, standing on one leg, lifting heavy objects, and walking in general tend to be difficult at times. Many women report that moving or turning over in bed is especially excruciating".
I treated mine at a very good chiropractor here in Oslo in one treatment. You will probably have to find good chiropractor in your area and get treatment.