I don't understand it

so I played roller derby for years.  years and years and years. From 2008 to 2014.  I never seemed to bruise.  I'd have these amazing falls, ones where people would gasp and wince, and what would I have to show for it?  Nothing.

Tuesday night at practice, we're working on transitioning, I'm going really fast, trip myself and fall.  A little bit later, we're practicing weaving through cones backwards, I trip over the last cone and fall on the same spot.

it's about 3" on the longer side, on my upper back right thigh

It kinda looks like a rain cloud.  If it were actually oriented on my leg in this direction, I'd outline it and draw lightning bolts coming from it or something.  Ah well.