unfortunately i don't know your daughter's age or medical history to be able to narrow down the hundreds of possible causes. i did have a case once where a child aspirated a small piece of crayon resulting in a severe cough. it took a bronchoscopy to find and remove it. if your daughter has not had an x-ray this should be ordered and perhaps it is time to see a pulmonologist (lung specialist) since her regular medical provider has not found the cause/reason for this violent cough.
my daughter has a cough for weeks can be violent at times and no other symptoms. 3 visits to dr office and not better.