Possible Miscarriage or PP Tissue

I am 6 weeks PP with my second baby. Around 2-3 weeks PP we had a couple accidents in the bedroom and I was terrified that I could have gotten pregnant so soon after having baby. My PP bleeding had stopped around week 2-3 and then I had 3 good days of bright red bleeding 4 days ago. I’ve been feeling nauseous and extremely tired lately and then this just falls out of my hoohah. Could anyone explain what’s going on? Is this normal PP or did I just miscarry? Do I need to take this to my OB to look at?