Someone tell me about this blood.

So it's 8 days until my next period according to this app, and I had a little random bleeding today. And last week sometime while I was ovulating. I figured the first amount of blood was mid cycle bleeding it lasted all day. But this little sporting is new lol. It's just a little bit an stopped. Why? I guess I should mention I'm sexually active atm. And had unprotected sex several times.