So I’m going on day 2 of brown discharge after what I thought was a normal period. Yesterday it was dark brown and today it’s lighter, I’ve never had discharge like this before so I’m confused as to what it is. Below is a pic of my tracker app, hearts are the days we had sex, green is fertile and red obviously is period.

Now normally my period is 4-5days max, Red blood stopped on Tuesday then I started this discharge. Has anyone ever experienced this ? Could it be implantation bleeding or something else ?