It could be one of several things. You haven't given a lot of information. Since I can't see the area in question, I might think along the lines of things that often appear in that area, that we see in the ER. ?possibly an ingrown
hair (foliculitis (folliculitis))~ those can get swollen and quite angry looking. Regardless, if it was on MY groin, and angry looking and an open wound I'd keep it cleaned, with a small 2x2 dressing on it til I saw my doctor about it next week. IF I had fever, yellow, green or foul smelling drainage, or red streaks coming from it, I'd get seen sooner than next week. Best of luck.