What Causes Swollen Lymph Node In Groin?

I have a lymph node in my right groin that has become swollen and tender 3 or 4 times in the last 2 months. It's the same exact spot every time. I'm also having a lot of night sweats, which is uncharacteristic of me. Medical history-wise, I am 33, 5'4", 110 lbs and I just had our third baby 6 months ago. Is this lymph node something to be concerned about?