Weird period help please

Okay so my period was "a week early" or so I thought... I started lightly bleeding the day after me and my boyfriend had sex and it looked light at first (pinky red) and then that same day later on it was normal darkish but a very small amount would come out. Anyways when I showered, a lot of blood came out and it felt and looked like a regular period. But then the next day everything that came out looked like sticky discharge but it was brownish and not blood. What is this?