Dee,

I had a very similar experience a few years ago, and spent 2 nights in hospital. I was discharged without a proper diagnosis as drs couldnt figure out what was wrong. Bloodwork showed nothing, as did abdominal ultrasound. I still wonder what it was, especially I ended up having an ecoptic pregnancy a couple of years later on the same side as the original abdo pain, so even now I wonder whether there was any correlation between the two. Now that Ive written it, Im not actually sure how that might help you, but in a nutshell, ive also had acute pain with no diagnosis, and I never had it again after that.

Hope your ok and it was one off thing,
Lisa