Gross smell 😖

Ok ladies I need help. I hadn't had a period in about a year and half thanks to pregnancy and breastfeeding. After stopping breastfeeding my cycle still didn't start back up for a while so I went back on my combination birth control pill to get regular again. It worked but last month was my first cycle and I noticed a really foul smell to the blood. I figured it was probably old blood from not having a cycle in a while and didn't worry, but now this month there's a bad smell again. Is this normal after pregnancy? What could be going on? No rude comments please, I'm very educated about how my body works but am a little puzzled by this and don't feel like spending the money on a copay to the doctor if I can get help here!