A bone bruise is something that's worse than a regular bruise, but it's a step down from something actually breaking. I actually had one of these suckers before on my wrist when I was a kid, and I genuinely thought it was bad until my older brother cracked the math on what happened.
However, when Mom comes home, I'll have to ask her if we can get it checked out, just to make sure nothing's actually broken, since the symptoms are pretty close.
