Is my sternum cracked or bruised?

I am 12 years old and I take gymnastics. I was on the bar attempting my Kip but I bent my arms and my sternum hit the bar really hard. It's been like 5 hours since it happend but it still hurts to breath and bend backward or just generally it hurts. My coaches said I probably just bruised it but it hurts really bad so I don't know. Please help me.