Is Headache Related To Chicken Pox?

Hi Drs, My daughter (6,5 years old) have had the chicken pox vaccine, however she catched the virus 10 days ago but it it was really mild, she gave it to her sister (3,5 years) and her brother (1,5 years) but it was even milder than hers. Anyways my question is, My older daughter has been suffering from headaches since the first day she had the chicken pox but it disappeared shortly, however since yesterday she is suffering from awful headaches through the day. is it related to the chicken pox virus? knowing that she's been good and no more pox over her body or anything, i am very worried, plz answer asap, what should i do?