hi I have not had twins, but had SPD with my last and went 9 days over due date. I suggest you see a physio for it as I got a support band to help with the pain. I did deliver vaginally but did need pethadine for the SPD not the actual contractions. I will say that my DH did push my hips together during contractions and that helped heaps with the pain early on.

Hope this helps.