I've have heard of people experiencing heat, pulling, dizziness, tingling and painful sensations in different parts of their bodies during their MRI's, but i'm only aware of MRI vertigo in the last 5 or so years being acknowledged as one of the more common side affect associated with MRI's.....off the top of my head, with MRI vertigo it's to do with the electrical currents flowing through the fluid in labyrinth, and temporary nystagmus there's more to it but that's all i'm aware of.
Searching the net will lead you to other's describing a pulling sensation but i don't think you'll find a conclusive explanation of why, sorry.
Hope that helps........JJ
I had to lay through a Cine MRI for a couple hours in December and I swear to the stars I was going to die from the amount of pain I was in. It was pulling so bad in my head, neck and stomach my legs were going numb from my butt down. I was screaming toward the last ten minutes so decided to hang on instead of ruining the whole thing. I can't medically answer your question other than more than likely something fell asleep and started to pull. And it was deferred pain to your stomach. Unless there was some chance you had metal in your abdomen. That's a thought as well. I wish you luck. Hope me, sharing my experience helps you somehow.