Firststork, thats good you went to your mw, always pays to check!

I had the exact same thing when pg with Clodagh except it lasted on and off right up to 10 weeks...esp after exercise.

It was really disconcerting adn we never did find out what it was. I just tried to put my feet up as much as possible....not that that probably did anything but it did help my peace of mind!