Help! Confused! Maybe TMI but no pic.

So I started metformin not that long ago. And I was wondering would I have ovulated before or after I started my first period on metformin. Last night I thought I was starting my first period it was reddish brown spotting so i put a pad on cause i thought i would fully start sometime through the night but then today there was nothing not even spotting anymore. Could I have already ovulated and it have been implantation bleeding?