What Do Prolonged Fatigue And Fluctuating Iron Levels Suggest?

My daughter is 47 years old. She has three teenagers and has been experiencing extreme fatigue for two years. She is seeing a hematologist now, but they have been able to pinpoint a diagnosis. Her hemoglobin count was 8 and her fourteen level was 1. She had an iron infusion in November but by the end of December her levels had gone back down They did an infusion in January and she is due for another tomorrow. She is just hoping to find out what is causing her problem. Do you have any suggestions? Thank you, Karen James