Just wanted to let you know that like a PP, I had this happen with DD when I was about 32 weeks. My OB met me at triage to check me and couldn't find anything wrong. She did ask if I'd had sex in the last few(?) days, which I hadn't. I didn't have any more problems and ended up having her on my due date. Hope this helps a little - I know it is so scary... Keeping you in my T&Ps.
Re: TERRIFIED...