I think I'm going through the round ligament pain. I had that same pinching pain when I was around your stage as well, and thats what I was wondering was twins. I'm starting to get the same pains, but they hurt more now, usually it happens if I stretch my legs the wrong way when I'm falling asleep. I had an u/s yesterday and one when I was 7 weeks. The baby is still in there with a HB so everything is fine.