Answer:
Factitious disorder imposed on another
Step-by-step explanation:
Factitious disorder imposed on another, which was usually referred to as Munchausen syndrome by proxy, is characterized by a deliberate initiation or falsely claiming of illness on someone, usually on a dependent a caregiver, causing the dependent to be admitted to be given medical care on such claims of being ill.
As stated in the question, Sharon created the appearance of diarrhea in her child, to get her admitted while pretending to be a worried and caring mother. Factitious disorder imposed on another is the appropriate diagnosis for Sharon.