Dear Madam, Hi & Welcome.
After having gone through the history of your beloved daughter I am of the opinion that she seems to be suffering from depression or
irritable bowel syndrome.
However, the possibility of
hyperthyroidism is less likely which is usually characterized by
weight loss despite of having a very good appetite,
nervousness, palpitations, fast and irregular heart beats, palpitations, sweating, tremors, thyroid swelling, heat intolerance, menstrual irregularities, etc.
So, in view of the above consult her treating physician after getting the results of thyroid profile and treatment accordingly.
hope this answers your query.