Recurrent pains in children are very common, with the head and belly being two of the more common sites. The pains often happen and then resolve until the next time. A search for a cause often comes up empty. Although the aches are real, frequently an organic cause just can't be identified. This can be particularly frustrating to the patient, family, and even the physician. If an organic cause can't be clearly identified, then psychological or environmental issues should be considered.
I would recommend that you touch base with her physician, filling in the details. A careful history and physical exam can be an important first step in helping to resolve these complaints without overdoing the evaluation or treatment.