Menopause: This is the most likely diagnosis given the symptoms of hot flashes and night sweats, which are classic symptoms of menopause. The headaches could be related to the hormonal changes occurring during this time.

Perimenopause: Similar to menopause, perimenopause can cause hot flashes, night sweats, and headaches due to fluctuating hormone levels.
Thyroid Disorders: Both hyperthyroidism and hypothyroidism can cause hot flashes, night sweats, and headaches, although other symptoms such as weight changes and fatigue are often present.
Anxiety or Stress: Anxiety and stress can lead to physical symptoms including hot flashes, night sweats, and tension headaches.
Medication Side Effects: Certain medications, such as antidepressants and blood pressure medications, can cause hot flashes and other symptoms as side effects.

Pituitary Tumors: Although rare, pituitary tumors can cause hormonal imbalances leading to symptoms like hot flashes and headaches. Missing this diagnosis could lead to serious complications.
Adrenal Insufficiency: This condition, where the adrenal glands do not produce enough hormones, can cause a variety of symptoms including hot flashes and headaches. It is critical to diagnose and treat to prevent adrenal crisis.
Carcinoid Syndrome: A rare condition caused by a neuroendocrine tumor, carcinoid syndrome can lead to flushing (similar to hot flashes), sweating, and headaches, among other symptoms.

Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodes of hot flashes, sweating, and headaches due to excessive catecholamine release.
Neuroendocrine Tumors: Other than carcinoid syndrome, other neuroendocrine tumors can cause a variety of symptoms including hot flashes, night sweats, and headaches, depending on the hormones they secrete.
Autoimmune Disorders: Certain autoimmune disorders, such as lupus or rheumatoid arthritis, can occasionally present with symptoms like hot flashes and headaches, although they are not primary symptoms of these diseases.