Discharge

Sarah-jane
Hi, I had some Brown/black discharge today, 11 days before my expected period according to my days app and 
13 days before my expected period according to <a href="https://play.google.com/store/apps/details?id=com.glow.android">glow app</a>, normal before period? I usually get it a lot closer to my period day, early period? 
Thoughts? 
Thanks :)