bleeding PP

i’m 3 weeks PP and after the first week i stopped bleeding entirely, i had a regular vaginal birth and everything has been normal up until this morning i woke up to period cramps/ borderline early contractions and heavy blood coming out and have been passing small clots, i can’t contact my doctor until monday but was wondering if it’s kind of normal or if i should go to the ER because as far as i know they got all of my placenta out so i shouldn’t be hemorrhaging or have anything happen