Hi Nell,
The only suggestion I have is to maybe go and talk to your physio. I was also having severe pelvic and groin pain, to the point of it being hard to walk. The pysio advised for me to hire this support 'belt' thing. It is made of wide strong elastic, and you wear it low around your hips. It basically helps hold things in a bit more, especially when the pressure of bubs is strecthing and pushing at your pelvis etc.

HTH