Sounds like a mild colic to me, since her bowels were moving. One of my colts coliced this last winter because he wasn't drinking enough water. He was having small bowel movements, I could hear gut sounds when I listened, but he was clearly in pain and wouldn't eat. He wasn't trying to roll, but I loaded him up and hauled his butt to the vet for a gallon of mineral oil and a shot of Banamine. He was fine after that. I had another mare get colicy this summer after getting into the feed room and having a little too much to eat. She was dripping sweat like she had a hose on her and was rolling when I got there and she got the same treatment. I didn't have to walk either one.
Do you think that alot of it depends on the type of colic you are dealing with? I always compare to humans:). Sometimes it helps a stomach ache to move around, some times that makes it worse.
When Rusty coliced this past summer, he wanted to lie down alot but didn't roll much. I let him lie, but sat on his neck to be sure he didn't roll. He didn't fight it much. Still not sure what the cause of his was. Nothing obvious.
Becky
I would have been reluctant to over-walk the horse that had been in the grain, because she would have been at high risk for founder.