Persistent cough.. Would alternative therapies help?
Ok, a disclosure: I am a current student of TCM (Traditional Chinese Medicine) and my answer will reflect that bias. Since you have seen a doctor, I will assume that your mother has been tested for such things as Pertussis and TB and such, though you should make sure. After that, I would advise you to take your mother to see a TCM practitioner who utilizes Chinese Herbal therapies. The condition you describe has a very obvious diagnosis in TCM (deficiency of lung qi–though there may be other factors as well), and could likely be treated with herbs, or a combination of herbs and acupuncture. Be sure your practitioner is well-versed in herb therapy, as acupuncture alone is unlikely to be sufficient.