Hi,
How is your daughter? Can you elaborate on the type and location of her headache? If there is no previous trauma, this could indeed be due to primary headaches or infectious causes that needs to be ruled out. With her symptoms, it is best that you have this checked by her doctor for proper evaluation. Direct clinical examination and additional tests including imaging studies and blood tests will help determine the underlying cause. Take care and do keep us posted.
I used to work at a pediatric clinic. I wonder how bad your daughter's headaches are. Are they debilitating her? Are they bad enough that she is crying? Has she hit her head or fallen recently? Your daughter needs to be seen by a doctor as soon as possible. This could be any of a number of things. I've seen strep tests come back on kids who have no sore throat, but complained of H/A and nausea. I also know that pressure in the head, such as post concussion, after a fall or head injury can cause those symptoms. Or if the headaches are bad enough it could be migraines. Some girls who are migraine prone, will start getting migraines as soon as they start menstruating or soon after. Any way, don't wait any longer if the symptoms persist and get her seen by a dr.
Let us know what is going on and good luck.
Lilyrose77