@intels5: Period pain can spread beyond the abdomen to the back and thighs, lasting up to three days and interfering with everyday activities. It happens when the uterus contracts during menstruation, but painful periods can also be linked to conditions including endometriosis, adenomyosis, fibroids or pelvic inflammatory disease. The NHS advises seeking medical assessment when pain prevents normal activities or periods become more painful, heavier or irregular. Treatment depends on the cause and may include anti-inflammatory medication or hormonal contraception. Persistent symptoms can lead to a specialist referral or an ultrasound to investigate the underlying problem. Source: NHS.