Postpartum Bleeding Starting Again??

I’m currently 5 weeks postpartum. My OB said postpartum bleeding can be off and on but I’m concerned. I hemorrhaged a few hours after birth and I’ve been scared ever since that it is going to happen at home. My postpartum bleeding stopped about a week to a week and a half ago and changed to the yellow discharge. Well I was feeling good yesterday and went shopping for an hour. Now today I’m sore where I tore and I’m cramping like I’m on my period (front and back cramping), and about four hours ago I went to the bathroom and saw that I’m bleeding bright bright red. It’s not enough to fill a pad or anything, but it’s scaring me.

Is this because I overdid it or should I be scared??

To Add: I had an ultrasound done around 2.5 weeks postpartum and the OB said she didn’t see any restrained placenta or fetal product.