Pubertal Changes: During puberty, boys can experience breast tenderness and swelling due to hormonal fluctuations, which could explain the puffy sore nipples. Frequent headaches could be related to stress, hormonal changes, or other non-specific causes common in adolescence.

Hormonal Imbalance: Conditions like hypogonadism or hyperthyroidism can lead to breast tissue growth (gynecomastia) and potentially cause headaches due to hormonal imbalances.
Medication Side Effects: Certain medications, such as those used for ADHD or depression, can cause breast tenderness and headaches as side effects.
Stress and Anxiety: Stress and anxiety are common in adolescents and can manifest as physical symptoms, including headaches and potentially breast tenderness due to muscle tension.

Pituitary Tumors: Although rare, pituitary tumors can cause hormonal imbalances leading to gynecomastia and headaches due to increased intracranial pressure.
Testicular Tumors: Some testicular tumors can produce human chorionic gonadotropin (hCG), leading to gynecomastia. Headaches could be unrelated or due to metastasis in advanced cases.
Hyperprolactinemia: Elevated prolactin levels can cause gynecomastia and headaches. This condition can be due to a prolactinoma (a type of pituitary tumor) or other causes.

Klinefelter Syndrome: A genetic condition that affects male development, leading to features such as gynecomastia. Headaches might not be directly related but could occur due to various reasons.
Familial Gynecomastia: Some families may have a predisposition to gynecomastia due to genetic factors, which could be a consideration if there's a family history.
Adrenal Gland Disorders: Certain disorders of the adrenal gland can lead to an imbalance of sex hormones, potentially causing gynecomastia and other symptoms like headaches.