Swollen lymph nodes in groin area

Patient: Hello, I’m a 28 year old lady.. I have a painful swelling that appears around the ground area every few weeks just before or after my periods. It last around 5 days and disappears sometimes its a lymph node and sometimes it’s a swelling that later removes puss. What do you think it can be?

Symptoms: Swollen lymph node around groin area, sometimes a swelling that removes puss that appear just before period or after