My 20 year old daughter has been feeling sick for
sounds like a common respiratory tract infection
welcome to the 'Ask a Doctor' service.
Her symptoms are consistent with a respiratory tract infection. In such cases persistent cough may occur and may last for a few weeks (up to two months at most). Since the general symptoms (body aches, etc) have improved, it seems that she's getting over it. If her cough does not improve within a few days then perhaps she should see a doctor. If the cough improves but does not wear off completely, you should give it some more time. Abdominal discomfort is common in patients with persistent cough.
If she develops more serious symptoms like fever, shortness of breath, faintness, etc then she should be examined by the doctor.
I hope I've answered your question. Please let me know if you need further assistance.