HI Mel,
I'm not pg now but I had this sooo badly with my 3rd baby (next was a premmie so I didn't have the chance!). What helped for me was cutting way back on exercise. If i had worked out, or even had a really good walk, later that day I could hardly walk. The pain was terrible.
My OB suggested seeing an osteopath or a chiropractor if cutting back wasn't enough for me. Luckily it was. I just had to accept that I needed to rest a lot with that baby. He also said it was probably because I had had 2 pregnancies very close together, and looking at your dates above I think that might be the case for you too . He said it was hormones--not pressure from bub.