What Causes A Hard Lump In Groin Area?

Hello, I have a hard, colorless, lump on my bikini line near the pubic bone right by the crease of my right thigh. It is extremely painful and seems like it has grown in length. It has no head and is not round. I am extremely worried. It is hard for me to sit or walk. I had chlamydia once but had it treated. What is this?!?