You are seeing a 30-year-old female in a primary care setting who has presented with a headache. During the history the patient informs you that this headache came on several hours ago and is on both sides of her head. She describes the pain as a tightening sensation which lasts minutes at a time. There is no photophobia or pain or nausea. On examination you note pericranial tenderness. What is the most likely diagnosis?