Hello,
i would get her to a natropath...Have her blood looked at by a good one, (you will need to phone around to find one who does blood analysis) and blood typing. They should suggest some remedies including taking an acidophlous product to promote a healthy gut.
This can be serious if not looked at...I think it has gone on long enough to look at getting some answers.
After she is blood typed, you could consider reading "eat right 4 your blood type" I have had amazing results for myself and my children, by following these guidelines...My 7 year old son has intolerences and when we go too far off his "good" list, we notice more stomach pain and behavior issues.
Just some suggestions that you might want to try...
Let us know!!