Excersizing causinting?

Everytime I've excersized this week I've started spotting almost immediately afterwords. Like, at the beginning of the week, I did six miles on my roller blades and started spotting, and then yesterday I did another 10 miles. And as soon as I got home, I started spotting. I'm on Zovia for birth control and I've had problems with breakthrough bleeding being on it. I don't understand if maybe it's coincindence that I'm spotting after excersizing and that it's just the pill or if there's some other problem.