Rejection of feeds is very common in a child with diarrhea. But these child usually take fluids normally or eagerly. Frequent loose motions not mixed with blood and vomiting suggests she is suffering from acute gastroenteritis
. In most of the cases it is viral.
Now Its a good sign that she is responding normal to breastfeeding
I will suggest you to give some antiemetic like ondensetron as if vomiting persists it may lead to dehydration
Don't force for feeding but try to continue the feed.Give frequent breast feed with ORS in between.
Give her syrup zinc and probiotic
Watch for urinary frequency( 4-6 times a day), lethargy or poor oral intake .
If you notice any of these consult your doctor immediately.