I would definitely start keeping a food diary, many intolerance issues (especially dairy) manifest with tummy/gut pain.
But I would also DEFINITELY take her to the dr, and I'm not a run-to-the-doctor type of person. As EdnaMarie said, it's not getting better -- it's persistent. And from what you describe, it's a fairly new thing. A food issue would be more likely (not definitely, but more likely) to have manifested before now.
Heather, mom to Caileigh 12/06 and aspie ADHD prodigy David 05/98 :intact lact