I was on a barefoot run and I stepped on a rock yesterday morning, it still hurts.?

My heel hurts, it feels like a bruise, but there's absolutely no marks on my heel pad, it hurts when I put to much pressure on it. I'm gonna try and soak it in some epsom salt, if that doesn't work, i'm gonna wear my old running shoes to school on monday, and if THAT doesn't work I'm gonna start worrying. If any of you have some experience with this and can help me I'd appreciate it.