Hello! thank you for your query. For this case, to narrow down the possible causes, a lot of additional information is still needed. First of all, let me verify the data you have given, she lost 33 pounds(15 kg) in just a month? If yes, this is very drastic and not normal. Her weight loss, loss of appetite and weakness may be termed as cachexia/wasting syndrome. Cachexia may be seen in certain conditions such as cancer/malignancy, kidney disease, chronic heart failure and other progressive diseases. Here are some of the questions needed to addressed; 1. How old is she? 2. Is there any history of depression? 3. Was she diagnosed before of any heart, lung, kidney, gastrointestinal or liver problem? and is she taking any maintenance/current medications? 4. Is there any particular part of her body that is painful like throat pain, abdominal pain, chest pain or headache? 5. Is she vomiting the food because she does not like the taste or is it painful when swallowing? 6. Did she have any history of fever or an infection prior to the present condition? 7. Any history of trauma or accident that involved hitting her head? These are just some of the questions needed to identify the main problem. I suggest you bring her immediately to an internal medicine specialist for a thorough physical examination and history taking. For the mean time, please try to give her small frequent feedings, soft foods that are nutritious and easy to swallow. Give her frequents sips of water as well. If there are no allergies to any food and medication, you can give her Metoclopramide 10mg 2x a day to prevent vomiting. I hope this helps, a feedback is greatly appreciated. Thank you!