My DS1 (he's 7) has been complaining of having a sore tummy on and off for over a year now. I took him to the GP who also wasn't all that worried. I spent my childhood with the same complaint and it turns out I am most likely gluten intolerant (although I also have a hiatus hernia which didn't help things either!). I only worked this out recently and realised that DS1's tummy pains stopped when I changed our diets. It appears to be the answer for us! Our family has a history of gluten intolerances so I guess I should have worked it out ages ago lol!

Keeping a food diary is a great idea. Your DD could also be intolerant of something and hopefully you also work out what it is.