Spotting past 6 weeks PP

I stopped bleeding/spotting around 4-4.5 weeks postpartum. My discharge changed to pink/yellow then to green/yellow then now bright yellow. I would get gushes of yellow discharge if I coughed/sneezed or walked a lot.

I have been up doing more around the house the past two days after sitting and resting a lot the past 6 weeks. I am now spotting bright red blood the past two days.

I have been swabbed for infections (results were negative) and I had an ultrasound at 3 weeks postpartum (results showed nothing in uterus, only increase in blood flow to the uterus).

Is this normal? I will get a small gush of bright red blood if I cough (I have had a sinus infection and been coughing a lot). The spotting hasn’t come back today, and I’m having the green/yellow/tan discharge again.

Is there something wrong with me?? My OB hasn’t seemed concerned in the past. I go back for another follow up in a week about pelvic floor physical therapy and birth control options.