What causes pain in the back of the head for over a week?

Hi doctor,

My mother, aged 47 years, has had pain in the back of her head for more than a week. We did not give her Panadol because it does not suit her intestine. She also takes medications like Anafranil, Zestoretic, and Inderal for anxiety and blood pressure. She also gets panic attacks sometimes, almost gone for a month, but it has become more frequent since the headache came. Her headache occurs right at the back of her head on the left side and is sharper when she wakes up in the morning, and it sometimes feels like she is wearing a tight rubber band as her head feels very tight, and feels slight vomiting. These nine days, she was fine after the fifth day, and then it came back on the eighth and ninth days, which is today. We also gave her a neck collar which helped her feel better yesterday, but she removed it today as she felt tightness in her neck and head. My mother had migraines four to five years back, and they are almost gone as they come back rarely and go away after a short period. My mother also takes Neo carbon medicines sometimes for gastric problems when she feels the need. Please help me and tell me what I should do.