I'm sorry you and your daughter are having such a tough time.
You should start by talking to your family doctor (or pediatrician, whoever you'd go to for a checkup). Then, if necessary you might be referred to a neurologist. Don't feel disheartened that Tylenol and Ibuprofen aren't working. There are a lot of other options out there, particularly medications and treatments tailored to headaches. Also, kids are much more likely to get through headache problems as they grow.
DX: NDPH (2003-present), CRPS (1998-?) possible Abdominal Migraine (2010-present)
RX: Lamictal, Indomethacin, Propranolol, Provigil, Viibyrd, Oxycontin, Clonazepam, Zyprexa, Melatonin, Magnesium, Boswellia Serrata extract (Boswellic acid)
CPAP for mild sleep apnea
PRN: Ketamine nasal spray, Oxycodone