Hi. The other day, a lump in the crease of my left leg (groin area) popped up. I do not feel any pain. It is about the size of a grape. I know that there are lymph nodes on either side of your groin. Do you know why it might be swollen? The other day, for the first time, me and my husband had sex in the ocean, and a few days later, this popped up. Could it be related??