Check her liver function tests and if they are normal then give  some omez or domperidone preparation .

Unfortunately with multi drug resistant TB is difficult to treat and requires change of medications quite often, I would advise you to meet a pulmonolgist or a TB centre and treated. You should inform the treating doctor when she gets side effects such as vomiting on consuming the medication as it has to be changed. As for the weight loss, her appetite will be reduced at present but you should give small frequent meals as she is unlikely to tolerate high amounts of food at present. Kindly also avoid spicy, oily, deep fried and junk food. Kindly visit the pulmonologist at the earliest.