How do I tell if my thumb is fractured, broken or just badly bruised?

I'm a softball player at my school. Thursday, March 14th I was at practice. I was bunting a ball in a batting cage and the ball flew and hit my thumb. I felt a werid pain but kept on going until the end of practice. I went home and iced it and got a brace that I have been wearing since Friday. My thumb is kind of swollen and is black, blue and green where the ball hit. I can move it foward a little and no where else. Please help.