Suggest Treatment For Painful Lump On Buttocks After A Bad Fall

Hello I play soccer for my highschool and during training I landed on some cones. I'm a goalkeeper and we were doing diving drills. My whole weight 160 pounds landed on the stack of cones and I have a big lump it's not a bruise well it doesn't have any color it's just a big lump the size of a softball. The first 2 days it was just uncomfortable. Now 3 days later it is painful and when I walk I'm limping. The lump only appears when I flex my butt what can I do? I have practice tomorrow and I want to be good to go?