Is your girl always the same and doesn't like to eat? Mine is just like that. She can use 1.5 hr to eat a bowl of congee (quite thick) and sometimes not even half a bowl in 1.5 hr. She simply refuses to open her mouth, or spits out the food, or keep the food in the mouth without swallowing. I guess it just takes time and patience for her to improve.
But if this happens only these few days, maybe you should take her to the hospital and check if she has dehydration. My little niece (27mths old) was ill during the Easter holidays. She vomited whenever she ate, even when drinking water. At the end my sister took her to the hospital fearing she will have dehydration. She stayed there for a week before she fully recovered. If the medicine given by your doctor doesn't improve the situation, it's better to consult the doctor/or change doctor.