5 weeks and bleeding after Sex

Yesterday morning before church my husband and I had had sex. Maybe a hour later I started bleeding. More light spotting/light bleeding. I had some cramping and back aches but I’ve been having those issues. I had a csection a year ago with my second son. I was told that’s normal because my uterus is stretching and with all the scar tissue it can cause cramping. I’m still bleeding off and on but still barely anything. It’s looks like old blood. The color is sometimes pink or red/brown.