Morning Windy - I know its hard but try not to worry - I had similar experience 12 years ago - I was examined by a hospital consultant and was sent for an urgent scan the same day - it turned out to be a fibroid (non cancerous).
The 'period type pains' could also be Irritable Bowel Syndrome.
Its human nature to worry ourselves sick when sent for an 'urgent' something or other, but its good that your GP has acted so quickly.
I wish you well Windy - let us know how you get on.