Period Like Bleeding 2nd Week of Birth Control Pack

Can someone give me some insight as to why I’m experiencing period like bleeding while I’m taking the pill? I’m on my second week in the pack and I haven’t missed or been late on a pill.

The pill I’m on is progestin only. I never experienced this with the combination pill I was on before I had kids. I’ve read about breakthrough bleeding, but this is heavier than the last period I experienced!

Thank you.