Many people with FM also experience tummy troubles, including IBS and food intolerance issues.
I have both. Right now, I am on a FODMAP elimination diet (information at
www.ibsfree.net/ibsfree_at_last/).
This is to help me determine which fermentable foods cause upset to my stomach. I have been on it for five days, and I can already tell a difference: I dont have to make so many trips to the bathroom, and my belly doesnt hurt all day. No more cramping, either.
I would encourage anyone with such issues to try it. I will answer any questions I can if you are interested