If your friend is a beta thal minor, and going by the long time symptoms, one could assume there is some degree of anemia present and this will slow the physical recovery in terms of restoring energy levels. Often, if a doctor is asked "is anemia a reason" the doctor will say yes, but when asked about beta thal they will say no, even though so many beta thals minors suffer from anemia. Do you know what your friend's current Hb is? It may explain everything. Was chemo involved in the treatment?