Worried about 4 year old

I am new here and I am worried about my 4 year old daughter.  Since July, she has had bloody stools.  Sometimes the blood is obvious and other times, it is occult.  We have been working with a pediatric gastroenterologist to discover the cause, but so far, nothing.  She has undergone colonogscopy, EGD, barium study, x-rays, reducing substances tests and occult blood tests.  The occult blood is positive and the reducing substances test is positive, but everything else has been fine so far.  I understand the biopsy should have shown celiac sprue or other allergy type disorders.  I am so worried and unsure of what happens if they cannot find anything and she continues to have bloody stools.  She is usually healthy, however, she does have very bad stomach aches and a reduced appetite on occassion.  She has had tummy aches since she was very little.  She does look pale and has not gained weight in at least a year and a half.  She also gets headaches.  Has anyone's child experienced similar symptoms?  What questions should I ask?  There seem to be so many possible causes.