I'm don't see adult patients anymore, but it's really hard to tell based on the information you have.
They probably did a stool hemoccult test (to look for non-visible blood in the stool). If this were positive, going to see a GI doctor would be a good idea, especially in her age group. If it were negative, they'd still want to check GI, to rule-out the most serious things, but there could be other reasons for anemia.
In kids, plain old iron deficiency will cause anemia, and is one of the most common causes. Vitamin B12 deficiency can do the same, as, rarely, would folate deficiency. These types of anemias will cause the blood work to show particular patterns (small red blood cells with iron deficiency, as well as with chronic GI bleeding; large with B12 and folate). The statement that the blood tests were "whacked out" probably means it didn't obviously fit any of these patterns.
Bottom line is that only time and testing will tell. Good luck, and I hope it's nothing.