Atrophic Vaginitis: This condition is a common cause of post-menopausal bleeding, especially given the patient's age and history of menopause 10 years ago. The symptoms of minimal discharge and the fact that the bleeding has stopped support this diagnosis.

Endometrial Hyperplasia: Given the patient's history of post-menopausal bleeding and previous episodes, endometrial hyperplasia is a possible cause. This condition can lead to irregular bleeding and is more common in post-menopausal women.
Cervical Polyps or Lesions: The patient's history of cervical treatment (laser for cervical lesions) in 1985 and the current presentation of post-menopausal bleeding could suggest a recurrence or development of new cervical polyps or lesions.
Hormone Replacement Therapy (HRT) Side Effects: Although not mentioned in the medication list, if the patient were on HRT, it could be a cause of post-menopausal bleeding. However, without this information, it remains speculative.

Endometrial Cancer: This is a critical diagnosis not to miss, as it can present with post-menopausal bleeding. Although the patient had a previous episode investigated without finding a cause, the recurrence of symptoms warrants further investigation to rule out endometrial cancer.
Cervical Cancer: Given the patient's overdue cervical screening and history of cervical lesions, cervical cancer must be considered and ruled out, despite being less likely than other causes.
Uterine Sarcoma: Although rare, uterine sarcoma can cause post-menopausal bleeding and must be considered in the differential diagnosis to ensure timely diagnosis and treatment.

Uterine Arteriovenous Malformation (AVM): A rare condition that could cause post-menopausal bleeding, although it is less likely and typically presents with more severe symptoms.
Metastatic Disease to the Uterus: In rare cases, metastasis from other cancers can cause post-menopausal bleeding. This would be considered if the patient had a known history of cancer, which is not mentioned in the provided history.